Wait. 'Moths, Myths, and Mosquitoes' was written by Marc Epstein.
Oh dear. My conspiracy detector just went off scale.
The Bab was no typical prophet. He was confined in stocks for seven years in a sewer, and IIRC, was held captive for over 40 years, because he would not recant. If I might regard any men sincere, Bahaullah would top the short list.
I have been in tunnels beneath cities large and small, and the diversity of purposes for which they were dug does not approach the myriad purposes which they subsequently served, from burial catacombs to drops for press gangs staffing privateers. I doubt that most villages don't have subterranean tunnels, because they're so damn useful.
One guy with a shovel isn't going to dig much more than a secret hideout, but I am unaware of any such undertaking so limited in personnel. Dyar's digs either are of little import, or he was not alone in his travails. Fortunately we are blessed today with ground penetrating radar. Any that want to find out more, can.
Thanks!