Foul mouthed little c*ck womble yes and clearly breaking the law, however the 'big man' or whatever assaulted him. Besides grabbing him, you catch a glimpse of the man throwing the kid quite violently to the ground. Not even bouncers can necessarily get away with that and they have to be licenced just to lay a finger on someone without risking prosecution.
In regards to the behaviour of the conductor, his conduct seemed fairly reasonable, however I do think it's quite possible that a mistake was made with the young lads tickets and the conductor tried to resolve that before he asked him to leave, or possibly made him leave the train so that it could be sorted out.
Personally more often than not I've found railway staff to be complete jobsworths. I've had a couple of awkward encounters myself with them where common sense is thrown out of the window in the interests of 'revenue protection'. My experience has taught me that most of these train staff care little about the welfare of their passengers. I had one try and kick me off a train once half way through a four hour journey during the winter because even though I had my ticket, I had left my young persons railcard at home.
Sadly I had no money or cards on me (stupid I know) and made him aware of this and tried to be as polite as possible to him, but he insisted I get off the train. Eventually I managed to persuade him to let me continue on my journey, however he made me fill out a slip of paper where I agreed to pay the maximum fare possible (£50) as a penalty charge, when my original ticket was £5.
I'd hope no elderly people are treated like that for what is a honest simple mistake. I'll bet though plenty of old people have been left out in the cold because they made a mistake with advance fares or something. The train operators have designed a bloody confusing system and introduced really restrictive terms onto their cheapest tickets. What do they expect to happen?