tl;dr: Lots of people are selfish ****s, however they're travelling.
Ideally the train companies would be able to just say "you can't carry bikes on trains if the service is busy during the olympics, here is a non-exhaustive list of potentially busy times", rather than introduce blanket bans.
Slightly less on-topic:
He wasn't hurt, his helmet broke the window. Other than a bruised ego, he was fine.
I feel I should point out that, not only am I a bus driver, but I'm also a car driver (and I do a lot of driving), trained as an HGV driver (only class 2 so far though), and most importantly, I am a cyclist - so I can see things from multiple points of view.
I have no issues with most cyclists on the roads, but there are the select few - mainly the 'I'm entitled to use this road, so I shall use all of it, and bollocks to the rest of you', or the 'I don't care what's going on around me' (particularly with headphones on) that are particularly bad, and it never ceases to amaze me how unaware some are of the dangers of the roads, but that's a rant for another time.
That's more reassuring. The image "his head went through the back window" conjured wasn't a pretty one. Unfortunately, he's likely to externalise the blame for the event on someone else, so it's not going to improve.
The basic problem is that people are selfish and ****s are ****s. It doesn't matter if they're on a bike, trying to take a bike on the train during peak hours, or putting luggage on seat. Unfortunately, most debates seem to quickly reduce to making absurd generalisations, like:
You wouldn't mind if they paid road tax and acted in a responsible manner but they want everything and for free.
Roads aren't paid for by VED, and if bikes paid VED, it should be Band A. I agree with you that cyclists should pay their Income and Council tax to pay for the roads, and that irresponsible road users should be dealt with. The cyclist specified in your example sound potentially inconsiderate, but I wouldn't say irresponsible (cycling 2-abreast shouldn't affect overtaking potential, but if a sufficiently long queue had built up, and a suitable passing point existed, then a considerate group would give way).