Register Taxonomy earlier so it can be used in functions.php and admin-ajax.php

This is a follow up to this post, outlining why I can not use the get_terms function while in functions.php (actually calling via ajax/admin_ajax.php).

I can grab the terms (custom tax) on any post, on any page, except when in my ajax function. I receive the dreaded ‘taxonomy does not exist’ error when dumping the value of get_terms.

The problem is, the taxonomy is registered after I call the function to find the terms.

The question is, how do I register the tax early enough so I can use this function? My code to register the custom post type and taxonomy is first in my functions.php (included via an external php to keep functions.php clean)

/************************************************ 
*
* 1.0 ------------------ Events ----------------
*
************************************************/


// 1. Custom Post Type Registration (Events)
add_action( 'init', 'create_event_postype', 0 );

function create_event_postype() {
  $labels = array(
    'name' => _x('Events', 'post type general name'),
    'singular_name' => _x('Event', 'post type singular name'),
    'add_new' => _x('Add New', 'events'),
    'add_new_item' => __('Add New Event'),
    'edit_item' => __('Edit Event'),
    'new_item' => __('New Event'),
    'view_item' => __('View Event'),
    'search_items' => __('Search Events'),
    'not_found' =>  __('No events found'),
    'not_found_in_trash' => __('No events found in Trash'),
    'parent_item_colon' => '',
);

$args = array(
    'label' => __('Events'),
    'labels' => $labels,
    'public' => true,
    'can_export' => true,
    'show_ui' => true,
    '_builtin' => false,
    '_edit_link' => 'post.php?post=%d', // ?
    'capability_type' => 'post',
    'menu_icon' => get_bloginfo('template_url').'/images/icons/events.png',
    'hierarchical' => false,
    'rewrite' => array( "slug" => "events" ),
    'supports'=> array('title', 'thumbnail', 'excerpt', 'editor', 'custom-fields') ,
    'show_in_nav_menus' => true,
    'taxonomies' => array('post_tag', 'tf_eventtype')
);

register_post_type( 'tf_events', $args);

}

// 2. Custom Taxonomy Registration (Event Types)
add_action( 'init', 'create_eventtype_taxonomy', 0 );
function create_eventtype_taxonomy() {

  $labels = array(
    'name' => _x( 'Event Type', 'taxonomy general name' ),
    'singular_name' => _x( 'Event Type', 'taxonomy singular name' ),
    'search_items' =>  __( 'Search Event Types' ),
    'popular_items' => __( 'Popular Event Types' ),
    'all_items' => __( 'All Event Types' ),
    'parent_item' => null,
    'parent_item_colon' => null,
    'edit_item' => __( 'Edit Event Type' ),
    'update_item' => __( 'Update Event Type' ),
    'add_new_item' => __( 'Add New Event Type' ),
    'new_item_name' => __( 'New Event Type Name' ),
    'separate_items_with_commas' => __( 'Separate event types with commas' ),
    'add_or_remove_items' => __( 'Add or remove event types' ),
    'choose_from_most_used' => __( 'Choose from the most used event types' ),
);

register_taxonomy('tf_eventtype','tf_events', array(
    'label' => __('Event Type'),
    'labels' => $labels,
    'hierarchical' => true,
    'show_ui' => true,
    'query_var' => true,
    'rewrite' => array( 'slug' => 'event-type' ),
));
}

Here is some pseudo code to show how I’m calling this function

from a custom page, I call a function via AJAX (ajax-admin.php)

$.ajax({  
            type: "POST",  
            url: "<? bloginfo('url'); ?>/wp-admin/admin-ajax.php", //Built in WP AJAX
            data: data, 
            success:  function(data){
                         //console.log('search complete');
                         $("#event-list").html(data)                                                         
                         }  
    });

Here is the function that calls a custom query, and where get_terms fails.

/****************************************************************
*
* 1.0 Calendar AJAX Queries
*
****************************************************************/
// if both logged in and not logged in users can send this AJAX request,
// add both of these actions, otherwise add only the appropriate one
add_action( 'wp_ajax_nopriv_calendar_search', 'calendar_search' );
add_action( 'wp_ajax_calendar_search', 'calendar_search' );

function calendar_search() {        
        $args = array(
            'post_type' => 'tf_events',         
            'post_status' => 'publish',
            'order' => 'ASC'
        );

        $query = new WP_Query( $args ); 

        // - loop start -
        if ( $query->have_posts() ) {

         while ($query->have_posts()) : $query->the_post(); /*Shows the posts that are available. */

                //Event Type
                $cats = get_the_terms($post->ID , 'tf_eventtype'); //the function that fails. All other custom data works fine 

                echo 
                '<article class="post" id="post-'. $post->ID . '"  itemscope itemtype="http://schema.org/Event">                       
                   <time></time>
                   <h2  itemprop="name" class="entry-title"><a href="' . get_permalink() .'">'. get_the_title() . '</a></h2>                
                   <div class="entry">
                     <p itemprop="location">';
                       if($cats) foreach($cats as $cat){ 
                            echo " | " . $cat->name;
                       }
                       echo 
                     "</p>  
                   </div><!--#entry-->
                 </article>";

            endwhile; 
         } else {
            echo "<h2 class='month'>Sorry, no events found!</h2>";            
          } 
        die(); // this is required to return a proper result      

}