Same thing happened to me few years ago in a sanctuary* the guy kill a gravid garter snake right in front of his son and he told him snake don't deserve to live and this only few seconds after to get out of their car.

I took few minutes to tell his son ....do you want me to show you another bad exemple ....Do you want me to do the same thing to your dad???
I was very mad!But I tell to the dad ,you don't deserve to take a walk in a sanctuary go take a walk somewhere else but not here and I drive him to his car ...He was lucky ....needless to say ....

Hope his son learn something on that day.....