As I understand it, it's a "depends how you look at it answer." You are correct in that if ND wanted to stay independent in football and switch conferences tomorrow for the other sports, the GOR only applies for those non football sports. The catch is that the GOR also says that if ND ever decides to stop being independent in football, it HAS to join the ACC. So does the GOR then apply to the football program after it joins and decides to leave? Don't know. Maybe the case is that if they want to switch to the B1G for football, they have to technically join the ACC for 30 seconds and then can immediately pay the exit fee and leave. They may not be stuck with the GOR for football (only with exit fee) but would still have to pay the GOR for all the non football sports.
It may end up being an academic argument. If ND does decide to join the B1G for football, the ACC is 1000% dead anyways and a bunch of ACC teams will try to flee to other conferences ASAP. May not be an acc in 3 years so they never have to send the GOR money for any sport.
Many of us said for years that Swofford was an incompetent dunce, but Blake James made him look like Einstein by comparison. No better proof than this whole situation.