Is this safe?

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE extension SYSTEM "ext-1.0.dtd">

<extension engine="1.0">
    <id>kt_group_leader</id>
    <title>KT Group leader</title>
    <version>2.61</version>
    <description>Adds group leader who can add users to his group.</description>
    <author>Kushi Themes</author>
    <minversion>1.4</minversion>
    <maxtestedon>1.4.2</maxtestedon>
    <install><![CDATA[
        if (!$forum_db->field_exists('users', 'group_leader'))
            $forum_db->add_field('users', 'group_leader', 'TINYINT(1)', false, 0);

    ]]></install>

    <uninstall><![CDATA[
        $forum_db->drop_field('users', 'group_leader');
    ]]></uninstall>

    <hooks>
        <hook id="pf_qr_get_user_info"><![CDATA[
            //mark mod as admin if changing group and have permission to do this
            if (isset($_POST['update_group_membership']) && $forum_user['group_leader'] == '1')
            {
                $forum_user['g_id'] = FORUM_ADMIN;
                $temp_mod_as_admin = true;
            }
            else
                $temp_mod_as_admin = false;
        ]]>
        </hook>
        <hook id="pf_change_group_form_submitted"><![CDATA[
            if ($temp_mod_as_admin && $forum_user['id'] == $id && $user['g_id'] == FORUM_ADMIN)
                message($lang_common['No permission']);
        ]]>
        </hook>
        <hook id="pf_view_details_user_info_end"><![CDATA[
        if (($user['g_id'] == $forum_config['o_default_user_group'] || $user['g_id'] == $forum_user['g_id']) && $forum_user['id'] != $id && $forum_user['group_leader'] == '1')
        {
            // Setup form
            $forum_page['group_count'] = $forum_page['item_count'] = $forum_page['fld_count'] = 0;
            $forum_page['form_action'] = forum_link($forum_url['profile_admin'], $id);

            $forum_page['hidden_fields'] = array(
                'form_sent'        => '<input type="hidden" name="form_sent" value="1" />',
                'csrf_token'    => '<input type="hidden" name="csrf_token" value="'.generate_form_token($forum_page['form_action']).'" />'
        );
        ?>    <form class="frm-form" method="post" accept-charset="utf-8" action="<?php echo $forum_page['form_action'] ?>">
        <div class="hidden">
            <?php echo implode("\n\t\t\t\t", $forum_page['hidden_fields'])."\n" ?>
        </div>
                    <div class="sf-set set<?php echo ++$forum_page['item_count'] ?>">
                        <div class="sf-box select">
                            <label for="fld<?php echo ++$forum_page['fld_count'] ?>"><span><?php echo $lang_profile['User group'] ?></span></label><br />
                            <span class="fld-input"><select id="fld<?php echo $forum_page['fld_count'] ?>" name="group_id">
        <?php
            $query = array(
                'SELECT'    => 'g.g_id, g.g_title',
                'FROM'        => 'groups AS g',
                'WHERE'        => 'g.g_id!='.FORUM_GUEST.'',
                'ORDER BY'    => 'g.g_title'
            );
            if (file_exists($ext_info['path'].'/lang/'.$forum_user['language'].'/kt_group_leader.php'))
                    include $ext_info['path'].'/lang/'.$forum_user['language'].'/kt_group_leader.php';
            else
                    include $ext_info['path'].'/lang/English/kt_group_leader.php';
            $result = $forum_db->query_build($query) or error(__FILE__, __LINE__);
            while ($cur_group = $forum_db->fetch_assoc($result))
            {
                if($cur_group['g_id'] == $forum_user['g_id'] || $cur_group['g_id'] == $forum_config['o_default_user_group']){
                    if ($cur_group['g_id'] == $user['g_id'] || ($cur_group['g_id'] == $forum_config['o_default_user_group'] && $user['g_id'] == ''))
                        echo "\t\t\t\t\t\t".'<option value="'.$cur_group['g_id'].'" selected="selected">'.forum_htmlencode($cur_group['g_title']).'</option>'."\n";
                    else
                        echo "\t\t\t\t\t\t".'<option value="'.$cur_group['g_id'].'">'.forum_htmlencode($cur_group['g_title']).'</option>'."\n";
                }
            }
        ?>
                            </select></span>
                        </div>
                    </div>
                    <div class="sf-set button-set set<?php echo ++$forum_page['item_count'] ?>">
                        <div class="sf-box text">
                            <span class="submit"><input type="submit" name="update_group_membership" value="<?php echo $lang_profile['Update groups'] ?>" /></span>
                        </div>
                    </div>
            </form>
        <?php
        }
        ]]>
        </hook>
        <hook id="pf_change_details_new_section_validation"><![CDATA[
            $form['group_leader'] = (!isset($_POST['form']['group_leader']) || $_POST['form']['group_leader'] != '1') ? '0' : '1';
        ]]></hook>
        <hook id="pf_change_details_admin_pre_user_management"><![CDATA[
            if (file_exists($ext_info['path'].'/lang/'.$forum_user['language'].'/kt_group_leader.php'))
                    include $ext_info['path'].'/lang/'.$forum_user['language'].'/kt_group_leader.php';
            else
                    include $ext_info['path'].'/lang/English/kt_group_leader.php';
            
            if ($forum_user['g_id'] == FORUM_ADMIN && $user['g_id'] != FORUM_ADMIN && $user['g_id'] != $forum_config['o_default_user_group']):
            ?>
        <fieldset class="mf-set set<?php echo ++$forum_page['item_count'] ?>">
                    <legend><span><?php echo $kt_group_leader['Leader']?></span></legend>
                    <div class="mf-box" style="float: left;">
                        <div class="mf-item">
                            <span class="fld-input"><input type="checkbox" id="fld<?php echo ++$forum_page['fld_count'] ?>" name="form[group_leader]" value="1"<?php if ($user['group_leader'] == '1') echo 'checked="checked"' ?> /></span>
                            <label for="fld<?php echo $forum_page['fld_count'] ?>"><?php echo $kt_group_leader['Leader label'] ?></label>
                        </div>
                    </div>
                    <input type="submit" name="update" value="<?php echo $kt_group_leader['Submit group leader'] ?>" style="float: left;margin-left: .5em;margin-top: .2em;">
        </fieldset>
        <?php endif;
        ]]></hook>
        <hook id="vt_qr_get_posts, ul_qr_get_users"><![CDATA[
            $query['SELECT'] .= ', u.group_leader';
        ]]></hook>
        <hook id="vt_row_pre_post_ident_merge"><![CDATA[
            if (file_exists($ext_info['path'].'/lang/'.$forum_user['language'].'/kt_group_leader.php'))
                include $ext_info['path'].'/lang/'.$forum_user['language'].'/kt_group_leader.php';
            else
                include $ext_info['path'].'/lang/English/kt_group_leader.php';
            if ($cur_post['poster_id'] > 1 && $cur_post['group_leader'] == '1')
                $forum_page['post_ident']['byline'] = '<span class="post-byline">'.sprintf((($cur_post['id'] == $cur_topic['first_post_id']) ? $lang_topic['Topic byline'] : $lang_topic['Reply byline']), (($forum_user['g_view_users'] == '1') ? '<a title="'.sprintf($lang_topic['Go to profile'], forum_htmlencode($cur_post['username'])).' ( '.$kt_group_leader['Leader'].' )" href="'.forum_link($forum_url['user'], $cur_post['poster_id']).'">'.forum_htmlencode($cur_post['username']).'</a><img src="'.$ext_info['path'].'/bullet.png" style="margin-bottom: -3px;"/>' : '<strong>'.forum_htmlencode($cur_post['username']).'</strong>')).'</span>';
        ]]></hook>
        <hook id="pf_change_details_about_output_start, pf_view_details_output_start"><![CDATA[
            if ($user['group_leader'] == '1'){
                $forum_page['user_ident']['username'] = '<li class="username'.(($user['realname'] =='') ? ' fn nickname' : ' nickname').'"><strong>'.forum_htmlencode($user['username']).'</strong><img src="'.$ext_info['path'].'/bullet.png" style="margin-bottom: -3px;"/></li>';
            }
        ]]></hook>
        <hook id="ul_results_row_pre_data_output"><![CDATA[
            if ($user_data['group_leader'] == '1'){
                $forum_page['table_row']['username'] = '<td class="tc'.count($forum_page['table_row']).'"><a href="'.forum_link($forum_url['user'], $user_data['id']).'">'.forum_htmlencode($user_data['username']).'</a><img src="'.$ext_info['path'].'/bullet.png" style="margin-bottom: -3px;" /></td>';
            }
        ]]></hook>
        
    </hooks>
</extension>