I think if Ohio had wanted in CUSA, they could have arranged to make that jump in the recent reshuffling of conferences. Ohio has a lot to offer, and would have been more attractive than some of the other schools that CUSA ended up settling on. Therefore I think you are wrong, and Ohio would not "jump at the chance" to join CUSA. A more interesting question is whether Ohio would "jump at the chance if given" to join the AAC. It's not the conference it once was, but I personally think that it's clearly better than MAC or CUSA. Even then, I don't know if that's the future that Ohio fans want. I know some would like to go the other way, and drop to Division II or lower.
As for Marshall, as much as Marshall fans talk up how much they like CUSA, I think they would jump at the chance, if given. to leave CUSA behind.
Marshall fans would be excited to make a move to a better conference, not just leave CUSA behind. AAC and ACC would make sense because the teams are close and some of them are good. Marshall fans would only be happy if a move was made to AAC, SEC, ACC, Big Ten, or Big 12 (really not sure about that one actually). Marshall could never compete in Big Ten, Big 12, or SEC so I'm not sure how we would feel if hell froze over and we were invited to one of those conferences. AAC or ACC would be no brainers for us. Until somethinging like that happens though, we do like the look of our conference and the ability to travel to games in Nashville, Charlotte, Virginia Beach area, Kentucky, Florida, and Alabama.
A move back to the MAC would never be supported by Herd fans. While we have close ties to teams like Ohio, Miami, and Toledo the perception by the fans would be that the move would be downward and a step backward. I'm not saying that is realistic, but it would be the perception. Some fans are pissed that we have so many MAC schools on our schedule this year.
Who really cares though? This thread was started by an Ohio fan, because The Herd (an opponent of yours) was picked to win the conference division. Immediately Ohio fans started trashing the division and then somehow it got turned into bickering about MAC vs CUSA. Funny stuff.