I saw a USCG report but it didn't say if the boat was in gear or not . . drifting with the engine running. lights on?. If it was, indeed, drifting in neutral, maybe he fell off while getting the boat untied from the pier. But the mainsail looks a bit roughly stowed . . . was the sail up or partially up when they found the boat?
If he was sailing, maybe he was heading out. If motoring, maybe heading into Norfolk.
I still don't know why he left Annapolis when he did. It's still February! And, as far as we know, he's a stranger to the area and the weather . . . not like someone we know here who won't even let pack ice slow him down!