That is a designated anchorage on the chart and the ship has/had a harbor launch alongside it when I looked.
No doubt, it just is not commonly used.
Lot of reasons for a small bulker to anchor little used locations. It’s more sheltered than Annapolis, shorter run, easier and safer for launch or bunker barges access. May help the pilots with shorter time on board required since she’s close to Dundalk. Could be easier for tugs that are stretched due extra boats required for larger ships in extreme weather .
Hampton roads small bulkers often in anchorage’s the larger coal ships & Container ships don’t use. Big bulkers almost always at the deep open Cape Charles anchorage Container ships generally anchor offshore outside state waters. Single pilot vs two, one to inside anchorage 2nd to the berth.
It’s really up to the Pilots who do their best to satisfy the vessels requirements. CG almost always takes Pilots advice on anchorages.
Boats
AIS this morning explains anchoring. She left the berth & loaded stores etc at anchorage. Saves a days dockage, underway to sea now