I blew a keg of Scottish a couple days ago. It just so happens that I have one ready to keg. So im going to test the limits of laziness tomorrow and just open the blown keg, rack the new beer into it, seal, starsan the connects, and put it back into the kegerator.
Assuming the keg was nice and clean in the first place, I think you’d probably be fine. The only issue I can think of would be if any residual yeast sediment (or beer flavor) in the keg were to clash with whatever is going in there.
Done deal. I had about a half cup of trube in the keg. Just dumped it out, starsan spritz the posts and racked. Stuffed it back in the kegerator. Done. I’ll quote a helicopter pilot I knew. “Probably its fine.”
Done this a bunch. Never been a problem in my experience. I’ve only tried it with the same beer as was in the keg in the first place so for yet though.