It’s not even remotely a departure from liberal values to protest outside. It is to work towards disrupting/overpowering the event so that it can’t continue, or to be totally unconcerned that others are doing so because “it’s a small group” or “they have plenty of other outlets” as long as the speaker is from the wrong side.

How have we “come a long way” from Reagan doing it? No-platforming actions don’t require the backing of a democratic majority. A few self-righteous people get going and no one wants to burn political capital objecting. Making the disinvitation button available to a wider population isn’t progress.