He calls the foul, because it is the right thing to do. Such a person is a mensch. Menschs do not put personal self-interest above doing what is right. Menschs are not only looking out for Number One. Menschs admit when they are in the wrong, and they acknowledge talent and skills in others, even if it exceeds their own.
Menschs are friendly and good people who wish others well.
Too many people view the world in win-lose terms. Either they are up or they are down. This affects our feelings toward them, when we, in turn, are in a position to help them. We can all recall someone whom we could have helped a great deal with the simplest of actions, but we didn't do so, not because we didn't want to help the person, but rather because we remember the person not helping us, when it would have been trivially easy for them to do so. They were not there for us when we needed them.