Looking for a way to filter posts out of the main loop in the admin if they have a certain taxonomy term associated with them.

functions.php

<?php
/**
 * Hide Maker Faire applications from past faires
 *
 * In the past, CS had a method for only selecting the current 
 * faire for applications. We want to do the same here, and prevent
 * all applications from showing up in the edit screen.
 *
 * @global $query
 *
 */
function mf_hide_faires( $query ) {
    if ( is_admin() && $query->is_main_query() && 'mf_form' == get_post_type() ) {
		//$query->set( 'faire', '-328' );
		$tax_query = array(
			array(
				'taxonomy'	=> 'faire',
				'field'		=> 'ID',
				'terms'		=> 328,
				'operator'	=> 'NOT IN',
			)
		);
		$query->set( 'tax_query', $tax_query );
		return $query;
	}
}
add_action( 'pre_get_posts', 'mf_hide_faires' );