Fair point. I've actually posted on the FR conditions thread myself to let people know that access to the crag depends on keeping a low profile, I'd hate to see the place banned.
I don't think being there for 15 minutes after dark with an underpowered headtorch while making a conscious effort to be silent should have done anything to jeopardize access though. A full on night session with multiple flashlamps, ghetto blaster, and people screaming 'send it dude!' would DEFINITELY not be a good idea though!
Having spoken to the homeowner, his objection to climbers right now is entirely noise based.