That’s almost a gun control argument in its logic.
Saying “unacceptable” means nothing. It is very acceptable, and even necessary, as far as policemen not being killed in the line of duty. It doesn’t matter if only 1 in 1000 people they meet wants to kill them. He wants to kill them. So being protected from him is more important than being apprehensive around the other 999.
So, the old man pulled a shotgun, not a cane, and shot the policeman dead. Is that acceptable, either?