Nevermind. Solution found via a value operation subtract dial.

Basically created an empty master, adding a value operations subtract to the effected JCM tied to that master and linked the master off to the negative rotation of a bend parameter dependency. So the intended positive JCM is turned off when the bend goes into -1 degree of rotation.

I'll rinse and repeat as relevant, which actually kills several birds with one stone. The subtracts are easy to make, I was already adding a subtract off dial to each JCM (to be overall controlled by regional and a global offs)... in other words not an extraneous dial.