For what it's worth, there was moldy webbing on Silly Chimney when I started climbing at the Gunks in 2005. I'm no forensics expert, but I'd bet that this rap line has been there all millennium. It's a nice way to get to the ground in one rappeldescend without bothering with any rappelling from Double Crack, Airy Aria, Bonnie's Roof, and Ursula.
There was no anchor there in the 70's, 80's or 90's. And I fixed your quote for you.