In fact it does terminate if I wait long enough (long enough being about 10 seconds). Not really the user experience one would want though and I'd missed it because I had not been waiting that long.
That's indeed quite a lot of time nowadays, more so if when you exit normally (by calling the mainform's
Close or through the "normal" means) it doesn't happen. I know next to nothing about Macs so I can't help much more, sorry.