With tork table you mean the aluminum “carriage” you screw all other plates onto? Those are not perfect and for example when printing it warps because of heat.
For cnc the easiest way is actually just flattening it. MDF typically doesn’t warp that much because of humidity. (Especially if you get the water resistant type.
Also do know that the SM2 isn’t a device that will give you accuracy into the 0.001mm range. I have been using a piece of mdf as base plate for a few months now and with great success. I’m not taking it off. Just mounting the other plates on top of it. And that just works fine. Also much flatter workface for 3D printing. Have been working on an improved version for a while (Idea for quick switch bed: feedback requested) and it seems to work quite well so far. (once the bottom plate is mounted I don’t take it off anymore)
I know others have been using the cnc wasteboard as a bottom as well successfully. I don’t have the impression it warps a lot. Then again, I don’t see huge fluctuations in humidity or temperature in the basement where my SM is located.