not very likely that this person is one of the two lost at sea 40 miles off the coast in my opinion. prevailing winds are north westerly this time of year or in general, though tidal flow and current are also factors in where those two end up. besides that, it seem unlikely that a body drifted in on the tide and ended up behind the barrier islands or in the back bays and creeks.
much more likely that this person entered the water in the back bays, creeks or rivers and drifted out towards the location where they were found by the marina. there may not be a ton of access points up tide or current from the location, but there are certainly bridges, boat ramps other locations where this person could have entered the water. or from a boat.