I must say none of the broader conspiracy stuff being peddled really holds my interest, but maybe I can shed some modest light onto the confusion with Loom/The Dig.
Moriarty has stated that while he had the basic ideas for two Loom sequels, he was too burnt out from the original game's production to actually pursue them. Following Loom he spent some time in the educational division working on an ill-fated Young Indiana Jones game(s). That division was in a physically separate office, or maybe even separate building, from the regular "games group," which is why Moriarty has no insight on the Forge designs that were kicked around -- he wasn't there to participate. And when he came back to the LucasArts building and took over The Dig, he apparently wasn't interested in digging them up.
Interestingly, there seems to have been no less than two versions of Forge proposed. There's the one already mentioned, headed by Mike Ebert and Kalani Streicher (a duo that in the end never got the opportunity to design a SCUMM game, but ended up being instrumental in some 16-bit console classics), but there was also, apparently, an outline put together by Jenny Sward, Sean Clark and Mike Stemmle toward the end of Fate of Atlantis. Sward pitched it to no success, and Clark and Stemmle moved to Sam & Max Hit the Road.
Moriarty not working on the Loom sequels was his own choice, though it's possibly one he came to regret in retrospect.