Good point. I forgot about that possibility because I don't spend much time playing in Open mode.

The same thing tends to happen on stronghold carriers in Solo mode, I suspect because Frontier programmed the game to spawn a bunch of NPC ships eager to dock with those carriers when a mini-instance is created. You can be the only player within light years, and still have to wait several minutes for all those NPCs to leave before you can dock.

*facepalm*