Sometimes justice is served quickly.
Blocking roads or highways is not a peaceful protest. It is disruptive to those that need to travel.
It is also dangerous. Not just for the idiots walking on a highway at night, but for every driver that comes across them. Sure we all drive defensively, but you don't really expect to have to come to a sudden stop on a freeway. Yes we're all prepared and don't out-drive our headlights etc. But it still causes an unsafe slow-down and space compression of traffic. Their "protest" was literally placing others' lives in danger, not just their own.
I guarantee you some of the first words out of the witnesses/participants mouths to the responding officers were "...we didn't think something like this would happen..." The operative words there folks are "we didn't think." If they were backing Clinton, they haven't been thinking in a long, long time.