Imagine doing all this just to get your paws on the human Iruma, but then it turns out that Iruma rejecting his humanity in front of
Jojo Gyro Zeppeli Alikred back in chapter 421 wasn't a one-off, and that he's already biologically a demon, if not half-way there. His "human" form is now just his "power saving" mode, and he's perfectly capable to "devil trigger" back to the form he showed in chapter 421 any time he wants.
...would be funny.
Reminds me of that other time
another human who attends a school in the demon world fully rejects his humanity for his loved one(s) after some time of pretending that he's one of them with the feats (assisted by his own group of secret keepers) to prove it.