min-count-for-cat-list.php

<?php
/*
 * Plugin Name: Min Post Count for Category List
 * Plugin URI: trepmal.com
 * Description:
 * Version:
 * Author: Kailey Lampert
 * Author URI: kaileylampert.com
 * License: GPLv2 or later
 * License URI: http://www.gnu.org/licenses/gpl-2.0.html
 * TextDomain:
 * DomainPath:
 * Network:
 */

add_filter( 'get_the_categories', 'min_post_count_for_category_list' );
function min_post_count_for_category_list( $list ) {
	foreach( $list as $k => $term_obj ) {
		if ( $term_obj->count < apply_filters( 'min_post_count', 3 ) )
			unset( $list[ $k ] );
	}
	return $list;
}