AFAIK, the language is and was used in JB's projects. JB is just very picky about when he wants people to see things. He doesn't want outside voices influencing him and he still has some things he wants to think through. Doing that mostly solo takes time - it's not like the PL is the only thing he has been doing

If you are fine with getting there 80% his claim is correct. That he's using the language for his games proves it to me. Of course, if you require it to be both open and popular to be a success you kind of reach a stalemate. In a world where everyone can quickly whip up a language I would expect most to be closed to the public anyway.

I would like you to elaborate on how still being in closed beta is an argument against the thesis. To me it just looks like avoiding feature-requests, nitpicks and community interactions for a product he doesn't even want to sell.