Right now, homeless people are not customers, meaning they are not making money off of those people, when they could be if those people were actually renters.
It is absolutely not clear that this would be pound-foolish, and homeless people do have cash if you get them off the streets and back as productive members of society.
Well, yea in a larger sense they would but they don't have cash so you can't rent to them for any significant sums. This is why socialists critique the market system as irrational.