If you’ll pardon the slight tangent:
Maybe including this functionality into the often requested pose tool may work too?
Since it seems to be basically an editable gradient ramp tool, having an extra option to “convert to mask” might be an option as well.
I’m going off the assumption that it would work similarly to 3dcoat’s version of the tool, so if Stephomi has a different idea for it, maybe it won’t be applicable.