Hmm, well, it really depends on how competitive the school make it, I think. Just because your lo is very competative (and I do feel for you) that's no reason why no one else can take part. It's like saying that the school can't put on an end of year show because 1 kid is horribly shy.
The up side to something like this is that the kids become part of a team, the activities need doing etc, but there's also a sense of belonging, team work, fraternity etc. Your lo is gaining that side of it- he helped his friend because he is part of his team. Working on the "be good for goodness sake" as well as that is something we all have to do with our los
So, all in all, if the school are promoting it in a balanced way, then YABU