Not true, it was UConn and Dave Gavitt that were adamant about not letting Penn St. into the BE. At the time the then UConn AD Perno has zero interest in going D1 with football. SU did nothing to support adding PSU. BC AD Flynn was supportive of Penn St. joining as he did not want to lose a football contract with Penn St.
Yes, the DeFilippo kept UConn out of the ACC, but it started much sooner. BC opposed UConn getting into the Big East football league starting with their AD Gladchuk . After UConn was admitted, Gladchuk informed BE Commissioner that BC was pursuing the ACC. BE commissioner thought BC had no chance at getting into the ACC.
At this point the ACC can’t figure out what to do other than pray that ND joins full time. That’s a long shot unless ND can’t get a 70 million per year TV contract on their own.