Can I exclude disapproved members from search results?

There is a property on the user account you would need to update

EnableDisplayInMemberList = false

 or it can be changed in settings within the admin panel 

Disapproved members should be removed from search index when they are disapproved.  There will be a delay though, until the next time the search indexing job runs, perhaps longer if the search indexing job has a large number of items to delete/reindex.