Look, Disney has definitely done some shady things, but this... Feels like a stretch. A lot of the disputed details seem like they're either pretty common tropes of seafaring-based adventure stories, or just aspects of Polynesian mythology that both stories incorporated. It seems much more likely that this is a case of parallel thought.

And frankly, even if that's not the case, that's the argument Disney is probably going to use, and it's going to win, unless this guy can come up with some more specific details they stole, or some better proof at least.