As the car seems to have attacked a cyclist first, would you also say they were legally allowed to assault the car as self defense?
There is no attack in there; even if they touched (which I think happened but I'm not really sure), it was a nudge which didn't cause any harm to anybody. That is obvious to anyone. To be an attack, it must be purposedly launched with what the attacker thinks to be enough force to possibly cause some kind of damage; that was blatantly not the case.
But let's say, for the sake of the argument, that it was: then there was no threat whatsoever to the life of the cyclists, so much so that the woman tried to leave; hence, they were not allowed to use any force against her. And that is because of the US, because in most other countries there would be no possibilities for them to become violent in any way.
If the problem was the "damage" (which wasn't there, clearly) to the bicycle, the car had licence plate and insurance (neither of which are required to bicycles, it's alway interesting to remember), so they had no reason to try and block, stop or retain her in any way, since the car could be identified and reported, even more so with videos and witnesses. But we're talking about nothing, since there was no damage to the bicycle or to anybody.
Also, there was no reason for them trying to prevent her for going where she wanted to go, or to stop her in the first place.
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Again, what are we talking about? There is no possible serious alternative point of view here: we have a group of people acting outside the law preventing other people from moving around freely, and when one of the victims refuses to abide to an unlawful and arrogant request, one of the men of the group tries to push her into submission to his own unlawful will. When the woman refuses to abide for the second time, he starts screaming and the other men encircle the car of the woman; and when she tries to leave, refusing to abide for the third time, they actively try to stop her by making physical contact with the vehicle. Notice that, up to now, no damage had been caused to anything or anyone. They were actively try to stop her from going away, for no reason at all. When she refuses even this fourth imposition and pushes on, using the strength offered by her vehicle, they become violent and start hitting her vehicle and smashing it. But she manages to free herself anyway.
Think of it this way: imagine she was a pedestrian, and they tried to stop her unlawfully. Then she tries to pass and to push them aside, but they block her and start screaming. Then she tries to go another way but they physically try to stop her by putting their hands on her to stop her. Then she tries to free herself with a bit of force and escape, but they start beating her, until she manages to push them away with some shoving, escaping with some bruises.
Wouldn't you say she had been assaulted and attacked? How is it that if she is on her car, then you even think it was her fault?