> Zillow likely has a clause in their contracts with MLS/wherever else they get these pictures, that they cant allow the pics to be used for any other purpose other than for posting on Zillow. They are trying to enforce this since they have apparently gotten dinged by suppliers in the past.

You seem to be just guessing about what might be in the contract, but I'll run with it. Unless there's some affirmative duty to police in the contract, why couldn't they just ignore McMansion Hell? Ignoring is not the same as giving license.