I'm certainly not saying that the MAC schools are any great shakes, or "better" than the schools in CUSA, but moreso that the level of competition / national recognition is essentially the same at this point between the two conferences, the MAC's media deal is superior to CUSA's deal, and a move to CUSA wouldn't make sense from a geographical standpoint (travel costs for non-revenue sports, etc.).
I agree it's a little curious that none of the MAC schools have been mentioned for a move to CUSA, but none of us know what's going on behind the scenes. Maybe the MAC schools made it very clear early on that they're not interested and shot down any prospective moves. Maybe CUSA doesn't want a more northern footprint. Maybe CUSA would prefer FCS schools. Either way, CUSA has been a shell of its former self for a long time, and I'm certainly not upset that UB and other MAC schools aren't in the conversation for a jump to CUSA.