I'd agree with the above, gated, pretty much no access and an aura of mystery does not sit well with me either, I think the same applies to a lot of other cavers/mine-explorers too.
As for comments being helpful; I'm sorry but if everyone started pestering the authors of that chapter they would no doubt get p'd off - is one of the others "part of the in-crowd"? I'm more than capable of using Google, know a number of people in the caving world that could point me in the right direction, but should I have to, would it even be worth it? It's been made blatantly clear that only those "in the know", "true scholars" or "buddies" of the explorers will get in - a very disappointing state of affairs.
And yes, I'm in a couple of clubs, I did ask someone in one of those clubs, who basically said he was looking in to it (this was a few years back). It would appear he's still looking in to it as I've not heard anything, so the best I can say is that comments about who to contact are unhelpful. I'm not going to reveal the persons name, but he is well known and respected, so if he can't gain ground then what hope of anyone else.