While I do agree that if the key is not in range there should be something programmed in to realize this fact, your car is fine. 10 minutes of idling isn't going to randomly blow your engine somewhere down the line..
If you're really that unhappy with it, program the ASS default to OFF. Complaining to BMW won't get you anywhere.
..Also, there is an ASS update from the dealer that you may / may not have. If you don't have it, maybe it will address some of your concerns, but I am unsure of the specific functionality from the update.
2013 F13 ///M6 Sakhir Orange
2013 F30 335i Estoril Blue II
2008 E92 ///M3 Interlagos Blue
2007 E92 335i Montego Blue