I have no problem with sharing the places I know. Whether they be archeaological site or just routes into and out of the canyons that are not frequented by the masses. I do however usually use a quid pro quo system. Kind of a "you show me yours and I'll show you mine" type of deal. I owe you one for sure.
When I first started exploring the canyons in the late 70's the 15 min. topo maps had lots of ruins and sites marked on them. It wasn't until the second generation of 7.5 minute maps came out that someone in their infinite wisdom removed that whole layer of data. Effectively censoring what was already part of the public record. Fortunately I kept all my old 15 min maps and transfered the info to the 7.5 maps and later to my Nat. Geo. Topo CD software. This took forever to do. But that info is not lost.
I find it humorous that the NPS and BLM are so secretive about these sites. Because they really aren't secret. One of my favorite things to do is to go up to the backcountry rangers desk to get my permit and ask about a particular site. Usually a category II site. Generally they are supposed to give you either the location or name of the site depending on whether you already know where it is and want the name or know the name and want the location. Sometimes they do and sometimes the don't. Occasionally I'll ask about a category III site. Then I get to see the old deer in the headlights look come across their face. Priceless. When they claim no knowledge of such a location I break out my maps and show them where it is. It just makes them look like such fools.
I fully agree that these sites need to be respected and protected. But not by a bury your head in the sand and ignore it's existince. That's a "let's not build it and no one will come type of mentality". Which never works.
So, as I have said if you want my info I'm happy to trade. There are some site which I can't in good conscience just give you the location. I will however give you all the clues you need to find it yourself. Sort of a treasure hunt kind of thing.