Maybe it's just me, but this doesn't seem like anything really gamebreaking. You block the way your character is facing, and if you're not in blockstun, you're going to switch what direction you're facing when your opponent crosses you up. All I'm seeing is that you're doing normal crossup mixup. It's not beating crossup protection, because you're not getting crossed up and then getting hit while you're still in blockstun. If you couldn't be crossed up at all, things like F-Kouma sandoori wouldn't work.
I do think it's interesting that the game treats your inputs like you're facing the opposite direction after you hit crossup, and it opens up opportunities for mixups some characters might not have otherwise. But that's the discovery -- doesn't have anything to do with beating crossup protection, as far as I know.
I could totally be wrong about how crossup protection works though.