It's always a tricky thing to have to deal with, although sounds like this guy took the nuclear option.

It basically depends on the parent, and what they think is acceptable (or even possible) when dealing with their child.

Sat in 1F back from HEL on Sunday, and the young child behind me (not good with ages, I'm guessing 3 or 4?) was playing around with the tray table before take off and her legs were the perfect length to kick the back of my chair constantly. I let it go for 5 or 10 mins (we had a delay before start-up. ATC restriction) but after a while I turned around and asked the mother if she could ask her child to stop it. I made sure I said it quietly, and kind of covered my mouth so the child couldn't see what I was saying.

Luckily the mother immediately told her to stop, and explained why she shouldn't do it, and apart from the odd fidget the flight passed peacefully.

However, it could have all ended rather differently depending upon the mother's response. And as the 'victim' of the piece, I could quickly have turned into the villain.