Excellent question. I think it comes down to motivation. I don’t think “pious anger” has any place in government or the affairs of state, which is where we run into trouble.
When we have congressmen intimating that judges will “pay” for what they’ve done, that sends a signal that they’re advocating violence, not out of some sense of justice, but in a Biblical, religious sense.
The line is grey, but it shouldn’t have anything to do with anger.