Nonjudgment requires humility. "Have no confidence in your own virtuousness. Do not worry about a thing once it has been done. Control your tongue and your belly" (St. Anthony). And it requires patience, a patience that trusts that God will work all things out and that you are rarely competent to judge the path rightly. In fact, it knows that you by your own presumption will usually screw things up.
Nonjudgment, therefore, is nourished by a contemplative nonattachment to the false self.
If you're attached to the many masks of your false or fallen self, you'll be unable to judge rightly when necessary and instead will probably end up clobbering yourself and others.