Angel Island is a state park. There are several but less-protected anchorage locations around the island, but no anchoring that I'm aware of in Ayala Cove. There are boat berths for day use only and the moorage for day/night use. There are toilet facilities and trash cans ashore. ... Hate to imagine the chaos of unregulated anchoring in the cove, especially with the quirky tidal currents along with the frequent ferry services.
Well then, it looks like pretty much what I posted. The government, in this case the state, placed moorings and outlawed anchoring in the cove as a source of revenue. That is, unless they own the water or the ground beneath it. Usually that is public property, open to anyone.