It’s a little more complicated then that. He could be a safety hazard for other boats and travel lanes. And then when some boat calls in the contraption as a rescue concern, they have no way of knowing its him until they get to him. It could be some other idiot in a makeshift raft for all they know.
I guess they could just slap a GPS on the device that way they can warn other boats or ignore rescue calls, but that seems like a lot of work just to placate one dude.