+1 Admins only is too restrictive
I noticed this too. After a little digging, it looks like the function call to schedule the expiration event is commented out in version 2.3.1.1.
On line 1716 of post-expirator/post-expirator.php [#_scheduleExpiratorEvent($post_id,$ts,$opts);] should not have the hashtag at the beginning. If you remove the hashtag from that line, it should work. I hope this both helps you, and helps the developer fix it.
