[nickrego]

I think you have to consider the step / feint to 3rd base as stepping off / disengaging the Rubber for the sake of consistency, and here is why…

If a pitcher, while engaged with the Rubber, spins and steps towards 2nd base, and either throws or feints to 2nd base, isn’t the pitcher considered having stepped off / disengaged the Rubber ? YES.

The pitcher didn’t step “back” off the Rubber with the Pivot Foot in this case either. They stepped towards 2nd with the Non-Pivot foot, just as it has been described stepping towards 3rd with the Non-Pivot foot to throw or feint. If a pitcher made this move to 2nd, and then over threw to 1st into DBT, you’d awards 2 bases. So why would 3rd base be any different ?