Yes the potential exists, however with a tile roof unless you are removing tiles there will be no tie off point. Should there be scaffolding to potentially fall and roll to? Not cost effective with it being an all hip roof. Not discounting the message being conveyed, this is business as usual for companies that specialize in washing and treating roofs. Residential maintenance and construction is extremely cost prohibitive. On another note, not even a roofer would be tied off on a project like this, the risk of tripping over the lanyard leading to a fall is greater than if it wasn’t there.