SPOILERS ALL
I think Moody especially would be interesting, a really funny conversation that you can never be paranoid enough
(optional goal: Blow their arses off at first lecture like you did to Draco with moon landing)
Edit: good point by other user, Harry won't probably have time for teaching, so imagine you're just a random from muggle family and have above average knowledge about the Muggle world than other Muggleborn seem to have.
In his experimentation phase, Harry recognizes early on that magic (at the very least seems to) violate thermodynamics.
His next obvious step should be trying to bootstrap the wizard industrial singularity.
I guess the Doylist answer is pretty obvious, infinite energy makes you nigh omnipotent and we can't have that.
