The boys were being anti social and were clearly too young to be travelling alone, but can't be responsible for their actions. Their parents should not have let them travel alone.
The appropriate response would have been to contact the guard. They would have taken their feet off the seats sharpish if he'd refused to move the train.
The man assaulted a child, a violent sustained attack against a minor. He did have responsibility for his actions, unlike the kids, and he chose not to break the conditions of carriage, which gets you thrown off the train, but to break the law. Which gets you thrown in jail.
I really hope that none of you who are hurling vile insults at kids succeed in painting this violent man as a 'gentleman' ' pushed too far'.
Don't you realise the kids took a picture of the assault because they had literally no other choice?
Imagine, just for a second, being in a position where all you can do is record an assault you cannot physically prevent happening. Now imagine that happening when you are a child.
If he can violently assault small kids in public my blood runs cold to think what a man like that is capable of behind closed doors. I hope he gets found and jailed before he attacks anyone else.