<?php
/**
 * Set the default comment status for events to 'closed'.
 *
 * Could easily be adapted to target all post types or a different
 * post type.
 */
add_filter( 'get_default_comment_status', function( $status, $post_type ) {
	if ( 'tribe_events' !== $post_type ) {
		return $status;
	}

	return 'closed';
}, 10, 2 );