The intellect devourer is a Tiny aberration, which would normally make it immune to the 1st level spell charm person, but when it successfully uses its Body Thief ability on a Medium humanoid:
The intellect devourer retains its Intelligence, Wisdom, and Charisma scores, as well as its understanding of Deep Speech, its telepathy, and its traits. It otherwise adopts the target's statistics.
Does adopting the target's statistics include the monster type changing from an aberration into a humanoid, which makes it vulnerable to charm person?
What happens when a charmed intellect devourer is Charisma (Persuasion) check'd into teleporting out of its host's skull and it becomes a Tiny aberration again? Is it still charmed?