It was a Dietzel initiative. Without him, it never happens. And to answer the question your posed about playing them after we left softening the blow, as was done in football, the answer is "no".The ACC wasn't quite yanked out from under him. He was an initial supporter of secession (though I doubt he would have initiated it on his own), thinking that the program was on solid enough ground. Within a couple of years, he realized that such was not the case. I wonder if it would have made any difference if we had continued to play all of our old ACC rivals with some degree of regularity after we left. Please note that UVA's visit to Columbia on December 19 will mark the first time men's hoops will play the Cavs in a regular season game (non-tournament) in Columbia since we left the ACC!
Had we stayed in the ACC and did not have the internal strife between McGuire and Dietzel (and later Carlen), my guess is that Frank I would have turned the reigns over to Don Walsh. in the mid-to-late 70s. Walsh saw what was happening, and left.
Sadly, it's beginning to look to me like our recent run to the final four was a fluke.