I can work with that. But with the grail, even though Indy lost his eternal life by crossing the seal, his dad remained healed from the bullet wound. So I think there must be some properties(benefits, cures) than you can take with you from the island. Perhaps, as we discover why the final six are chosen and others remain on the island (I assume they’re alive still) we’ll get a clue about whether if what happens on the island stays on the island or not.