Filtering Event Categories with 'tribe_events_pre_get_posts'

function pnh_filter_tribe_all_occurences ( $query ) {

    //If we're in the admin, make no query alterations
    if ( is_admin() )
        return $query;

    // Get the event category slug
    $eventcat = (isset( $query->query_vars[Tribe__Events__Main::TAXONOMY] ) && $query->query_vars[Tribe__Events__Main::TAXONOMY] != '' ? $query->query_vars[Tribe__Events__Main::TAXONOMY] : '');

    //Check that the event category being called isn't one of the 3 we're excluding
    //(if it is, then don't do the exclusion)
    if ( $eventcat != 'music-club-listings' && $eventcat != 'art-exhibits-events' && $eventcat != 'theater' ) {

            //Add a tax query to exclude the Art, Club Listings, and Theater categories by all views (except those specific categories)
            $taxquery = array(
                array(
                  'taxonomy' => Tribe__Events__Main::TAXONOMY,
                  'field' => 'id',
                  'terms' => array(21,22,17),   //Art = 21, Club Listings = 22, Theater = 17
                  'operator' => 'NOT IN'
                )
            );

            $query->query_vars['tax_query'][] = $taxquery;
    }

    return $query;
}
add_action('tribe_events_pre_get_posts', 'pnh_filter_tribe_all_occurences',1000);