My Husband Can’t See My Viewpoint

son’s landlord wanted his house back and he came back to live with us. He wants to save a deposit to buy his own place. We can help by letting him stay for free, but my husband says no adult lives anywhere for free and he has to learn that. If my son was out spending wildly, I would understand, but he’s a sensible lad and we don’t need the money. How do I get my husband to see the quicker he gets the money, the quicker he moves out?