You don't have a right to murder criminals with your car, no matter how heinous their crime.
''accomplices''? Talk like that implies these protests are some elaborate trap to lure cars in and ambush them from all sides. Absurd, unless you've got some examples of this happening.
It's a gray area legally, which will ultimately be decided by a jury. This link discusses the legality in the case that the protest has no permit and is blocking public streets.
Fact check: Drivers don’t have the right to “plow through” protesters - Reuters
My point is that proving the bolded is difficult in incidents like this because it is patently obvious that drivers have a whole world of alternatives to plowing into a protest. The protesters are clearly at fault if they ambushed, chased (somehow) or otherwise trapped drivers in a way that prevents them from using alternative routes. In the situation in the OP the driver clearly had alternatives, and consciously chose to disregard them to put everyone around them in danger.
I'm happy to be proven wrong with an example, but I'm not going to hold my breath.