So people want to be in a tourney more than they want to be in your betserver, and you think that's a bad thing?
If people would rather be in a tourney, then why take that opportunity away from them just because you're not going to earn money on house and nudges..
Besides, 15 people isn't really that many, and if you make the server enjoyable enough, GMs globalling shouldn't be a problem.
Probably one of the stupidest suggestions I've seen in a while, sorry to say.