If someone posts a guidebook online - will hackers "chop it?"
About an increase in use at LC - It's definitely true that the parking lot gets full pretty early on good weekend days. Also keep in mind that parking lot is used for people going to the Split Rock area, and hikers taking the Old Minnewaska Road.
An increase in climbing at Lost City would impact the availability for those people simply because climbers do tend to come early/stay late.
If the preserve doesn't want the impact on Lost City, they could, if the wanted to, limit the number of Day Passes to climbers sold from that location. Of course, this would probably end up being a debate almost as big as the other "big issue" that flares up on this site with regularity - hahahah.
But.... If the preserve wants to limit the impact there - then I think limiting the Day Pass sales(or even limiting the number of Annual Pass climbers allowed on certain days) would be a pretty effective remedy.
Last summer, a couple of people locked their keys in their car at the LC parking area, and were waiting for a locksmith to come. I was talking to them, and pretty surprised to find out it was one of the person's very first times out climbing. The other person, the more experienced one, had gone to LC with a guide, who set up top ropes. That person learned how to set TR's and - since they only knew LC cliff top.... that was where they were climbing and taking their friends.
Perhaps the preserve should also consider the impact that is being sown through allowing guides to bring beginners/beginner groups out to LC?
Meanwhile - the local ethic IS for non-documentation. The preserve request is also for non-documentation. I just don't see how anyone can legitimately argue validity for publishing the information.