Interaction between an Intellect Devourer and a Simulacrum

Question

An Intellect Devourer has an ability called Body Thief, which states:

...the intellect devourer magically consumes the target’s brain, teleports into the target’s skull, and takes control of the target’s body. While inside a creature, the intellect devourer has total cover against attacks and other effects originating outside its host. 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. It knows everything the creature knew, including spells and languages.

If an Intellect Devourer takes over a Simulacrum of a Wizard, can the Intellect Devourer recover spells with a long rest, or is it beholden to the simulacrum rule:

The simulacrum lacks the ability to learn or become more powerful, so it never increases its level or other abilities, nor can it regain expended spell slots.

This literally just happened to us and we are stumped. I think the Devourer is a new creature and thus can recover spells, and would choose to gain the abilities but not the shortcomings of the new form.

Answer 1

The problem is in trying to apply Body Thief to the Simulacrum in the first place. The RAW does not support that.

The Body Thief Action for intellect devourer says:

The intellect devourer initiates an Intelligence contest with an incapacitated humanoid...

So if the Simulacrum spell creates a creature of type humanoid, it could be targeted by this action. But let's see what the spell description says:

You shape an illusory duplicate of one beast or humanoid... the illusion uses all the statistics of the creature it duplicates, except that it is a construct.

So it turns out, it is a construct, the resemblance of which to a beast or humanoid is "illusory". So, though it is a creature, the type of creature it is, is other than humanoid, and thus it cannot be the target of the Body Thief Action.