Alert Tuning for DataSource that has "Automatically Delete Instance" enabled?

I did a quick test with a dummy DataSource. I let it create a dummy instance and setup a custom threshold at the group level's Alert Turning tab. I then modified the DS to have no instances and the entry disappeared from the list. I modified the DS once again to report a different instance and the entry came back and kept the previously set threshold. So it does seem to keep your custom settings even if there are no instances.

I only tested the difference over a few minutes so you may want to test over a larger period of time (overnight/days). I also don't like how this causes possible hidden settings we might not be aware of. It might show up in a report though (didn't test). Interesting that the API does show it.