I never did hear any more on this. I am not even 100% sure it was in Southern MD. I keep Ch. 16 in several scanners and there are multiple repeaters throughout the state. I could not hear the boater but I could hear CG Baltimore. I dunno if the boat was afloat in a channel, up against the shore, or whatever.
If sinking, I would think they would investigate for loss of life possibility and hazmat. If in a channel I would think there might be loss of life suspicions and other mariner's safety concerns. It struck me kind of odd that they did not take more action on it. Maybe it was just floating around in a small inlet or something.
Also they had been putting out advisories looking for a 70YO Male boater in something like a 25' boat for the last 2 days. You would have thought they would have taken this a bit more seriously. Probably some things said by the boater that I could not hear.