Hi PerBonomi,
 
Great contribution! As Wendy_S mentioned, our users have been asking for something like this for a long time. 
 
I didn't realized I was having the same issue where the users were not deleted from the list. After some testing and google I *think* the issue is the form is interferring with the http request to the endpoint. 
 
I might have accidentally fixed the issue while using the .unload() event to call the endpoint. I was trying toremove the user when they click on a link or type a new URL directly on the address bar too. Here's the code.
<@liaAddScript>
		$( window ).unload(function() {			
			
			var url='${community.urls.communityPrefix}/plugins/custom/hp/${community.id}/collision-check-endpoint?id=${msg_id}';
    		$.ajax({        
    			url:url
    		});    		
		});
	</@liaAddScript> 
Hope that helps!