NCAA rules deal with players who receive scholarships, but they don't care that much about walkons. It sounds like there is a limit in the WCC for how many players can travel to games. One poster, I can't remember who it was, called them and was told 13 players can travel to WCC games. The 13 don't all have to be those on scholarship however. As far as I understand, all 18 can sit on the bench during home games. However, a couple may end up redshirting, and at any one time someone is probably going to be injured, so the exact players making the trip to road WCC games could change from game to game.
As far as forcing players to redshirt or transfer, that doesn't have to happen. Someone may choose to leave the program, but there is no reason anyone is going to be forced to do that. Every school has a prep team which almost always is purely non-scholarship players. Because we were so thin last year a couple of them ended up on the main roster (Pingree and Johnston) just so we could get to 12 players there. The difference this year is that we have so many players paying their own way this year who would normally get scholarships.