It’s not the landlords, it’s some poor schmuck they’re paying minimum wage to cold call all day. I guess you could try to move forward with the process to get to the people who are worth fucking with though.
“If someone wants to buy my house I would have to speak with them directly.”
Not even a remotely strange thing to say, if you were serious about selling you would upgrade that call. After that act interested and if you have time to spare, waste theirs. The longer they’re on the phone with you the less calls they can make that day and that’s less pulls at the slot machine.