If I was Player A and was in casual play, I would make a case that what Player B was saying was unfair since they are clearly a friend of mine. If I was in a tourney, I would just walk away from the table saying I am done as the person is unreasonable and I don't play leisure games for fun with unreasonable people. Life is to short.
Out of curiosity: shouldn't this be the other way around? ie. wouldn't one be more willing to walk away from a casual game with no stakes, rather than one at a tournament you (presumably) paid to enter?
I play casual games with friends. My friends are worth my time or I would not be friends with them and if I say "that's inappropriate", they will consider if it was a inappropriate or not. I am also more than okay spending time vigorously discussing with my friends why I think they are being inappropriate. (note, original draft used stronger language than "inappropriate")
At tourney, its at best an acquaintance and at worse a stranger. I am not really invested in the person and if that is the way they play the game, I don't want play with them. Its not worth the argument and I am not having fun playing them. Also, a couple of dollars and the potential to win some cardboard and plastic isn't really a major incentive for me to put up with that type of bull.
That being said, I am getting fond of a number of people that I frequently play at the local tourneys, probably wouldn't have them over for diner but would get a drink with them.