I always wonder if bear spray even have any effect on momma bears?
Discussion
I think if you were making a legit attempt to remove yourself from the area and you put a noxious cloud between her and yourself, it would be OK. It would be different if you were actively trying to stay put and threaten her young.
The problem is when you get unintentionally in between the mommy bear on one side and their little ones on the other. Then It's highly unlikely cloud of bear spray would do any good. The bear parental love is just too great to be beaten.