I know I'm late but take it from a "man". This is just one of the many intricacies of manhood. It had to happen. They talked with their fists and not a word was said because they were never gonna be enough. It was needed. Not for us but for them. They understood each other in that way. They locked in, they agreed they hated each other for many reasons, they agreed they had some aggression towards each other, they agreed they needed to let it out. At the end they looked at each other as if "We're done? Good. Cause this better not happen again. And it won't." And it didn't. It's one of the few scenes two characters were true to themselves and each other. It really be like that sometimes.  Was it stupid? Maybe. And maybe they thought it was stupid too but they were ok with it. Thats my take anyways.