Not to be a jerk but, for my Mom (and only for her, if she was still alive) I would have left it in the truck.
I understand about sticking to your guns (no pun intended) but you have to respect other people , ESPECIALLY in their own home.
If she was that bothered by it, I would respect her wishes.
What wishes?
From my understanding the mother freaked out then moved on to the next order of business.
I didn't read anywhere about anyone requesting that he disarm and leave the pistol outside in his automobile?