son's behalf.
I don't know if this is good advice, but it seems like acting out of spite is a tempting option here. For one thing, do not let them collect 185% rent.
Build a meth lab, store perishable food in there, do anything but allow the landlord to have 1.85x money from the same spot. Also, do not help them fill slots. Actively discourage people from renting there. Make sure anything they get from you comes at maximum cost and annoyance to them.
This is bad advice for your soul and peace of mind, but like, I'm not going to find someone a full-price-paying replacement customer to get a 15% discount and lose access to the space. Maybe just use his apartment as your family crash pad to host a rotating cast of visitors.
Finally, do not be afraid of litigation. You can do this without soul-destroying hatred in your heart. If their policy is fine, they won't mind defending it to a judge.