Exclude bbpress replies from search?

Is it possible to exclude ALL bbpress replies from search? Including replies isn’t helpful at the moment because it generates lots of near-duplicate results.

I’m applying this code snippet to try and exclude replies, but it’s not working. I think it only works for bbpress default search…

add_filter ('bbp_before_has_search_results_parse_args' , 'rew_topics_only') ;

function rew_topics_only ($args) {
	$args['post_type'] = bbp_get_topic_post_type() ;
return $args ;
}