The stranger had to be a mental case. I don't care how badly the child was acting up the fact that he thought he had the right to tell the mother anything; and the fact that he apparently doesn't know right from wrong, shows he's a nut case. "Poor him" - he didn't like hearing a kid cry
Oh, and "big, brave, man, him" - he'll take on a two-year-old. 
cosette, the same thoughts occurred to me about beating his own kids.