This is the classical go after the messenger, not the message attack. It sends a very strong signal to show who is "in charge" and what "may happen" when you try to challenge the status quo.
It does not matter that they now apologize or backpedal. They have already sent the signal and it is ear deafening. The political affiliation or wing or side does not matter. This type of behavior is found on all sides and is typical of a bully wanting (to stay in) power. The way to fight a bully is to expose the bully with unified front.