morally? Seriously. Step back a little and look at it from a landlords perspective. Airbnb can facilitate lease violations and that's okay, but helping Landlords identify lease violations is morally wrong?
Just because some folks might violate the terms of their {lease, rental agreement} does not mean ALL of them do. Your actions would hurt the honest hosts, as well as those in violation of their rental terms.
Don't be a schmuck. Seriously. You are not the moral police for those renters.
DISCLAIMER: I am an Airbnb host. I violate no rental terms, as I own my home.
But you're now suggesting that this injustice to landlords justifies harvesting Airbnb's user's personal information and then selling it? That's morally and legally questionable any way you look at it.