I will try it out and report back.
Update: doesn't fit, can't get the muzzle all the way in. Seems the frame of a TM9 is slightly taller than the frame of a Glock 17. The grooves don't seem to line up. I imagine with some modification on either the frame of the TM9 or inside the MCK that it would work, though I'm not willing to do so as I use it for my Glock 17. The charging handle seems to fit on the slide serrations despite the Glock 17's being straight and the TM9's being angled. However, because I can't get it fully in I can't really test how well it's holding on. Also, the magazines don't catch in the holder. Again, I'm sure with some modification they will.