93 is a different story, I think. It went straight down into the ground, didn't it. That could have resulted in the black box becoming little tiny piece of metal.
I have no idea what happened. It just seems odd that a couple of FF's, now they are retired, start to talk.
If the objective of this theory is to demonstrate a cover up, it would seem that the recovery of flt 93's flight recorder and the release of it's information would put a kink in the theory.