No, they can't. That's a rock solid anti-trust violation and isn't a barrier at all. A lot of people are saying we need to move now or be locked out forever. I don't believe that for a second. That's *literally* illegal.
Remember that the NCAA says you can't join FBS without an invite, but Liberty did it anyway. NCAA denied the UAC's request to be a football conference, but they did it anyway and were given an AQ. NCAA says you have to sponsor basketball to be a conference, but the PAC-12 isn't and is still collecting NCAAT credits.(grace period doesn't apply to this unlike number of members, before anyone says something)
There's a difference between patience and stagnation. It's very clear that in the next 2-5 years there's going to be a major shakeup when the courts mandate pay for play. I suspect several dozen low end programs will drop football, maybe out of D1 completely. That'll force massive realignment. The Dakotas, Montanas, Idaho will be on the right side of that, much of their existing conferences won't. There's some ambitious up and comers in the WAC too. I'm willing to wait a few years to see if that happens vs burning bridges to join a crappy southern conference immediately.