I’m guessing that by that you mean it doesn’t have the elastic sides that the nylon holster has? In this case, aye, it won’t fit.
I’m out of ideas. The TN12 is easily one of my longest lights, only competing with the C8, and the latter has a huge head, bigger than the M1’s. The only other tube light I’ve tried with the TN12’s holster is the Convoy S2 (not S2+, mind you), and while it fits laterally, it’s too short for the flap to secure it. Guessing that’s a no-go IYO.