It depends on your league and if it is local or not. Typically the commisher should get a small fee if he works as commisher. If you spend two to four hours recruiting and expenses are involved in getting the fees and paying out the winnings, the commission should be enough to cover those expenses.
The commission however should not be used as an income generator.
If you have a local league, sometimes the commission includes the draft party expenses and the post party expenses.
He playing it like Vegas, where if you play a game, he gets 10%. Problem is this. Its yahoos game not his, and yahoo does not take 10%. I suggest you void your team asap, since he getting his $ back to be in the league you all pay to be in or more.