The problem with the bullies like Adam is that referees come down so hard on retaliation. It's impossible to have a go back. When I was playing Rugby I was always taught that if anyone had a go at me hit them, just once, and then say 'do that again I'll hit you again'. Invariably it worked, people would leave you alone. I was often talked to by the ref but was never sent off. On one occasion I was playing for an under 19 side against Petersfield 3rd team, a team of players who had been around the block who were reaching the end of their playing time. We had one overage player which was allowed in those days who had also been around the block. We were getting a hard time in the front row, all the eye gouging etc. when KJ, the over age player, said OK, next scrum don't go down, just wait for them and lift your knee, make sure it connects. Next scrum, three blooded noses straight in front of the ref. He did no more than to say right lads, that's equal now, anymore someone will have to walk. After that we had good clean scrums and had a fair old drink together afterwards. My point is that if a player who'd fallen victim to a thug such as Adam was given a licence to slide into him with studs raised and chop him down, it would stop people like Adam in their tracks. Retaliation is looked at as worse than an original offence, independent of how violent the original offence was. Personally I think measured retaliation could be of benefit to the game. Once the score is settled the ref could easily say enough is enough lads, any more someone will walk.
I can remember when I was still quite young playing in a club game. I got thumped by the open side flanker. When I mentioned it a half-time, I was told that I had to thump him back at the first opportunity or I wouldn't get any respect. I really wasn't sure about this, but did as I was told. After I'd smacked him one, he initially looked surprised, but then just grinned. As you say, we all had a good piss-up and a laugh about it after the game.