To play devil’s advocate, it is perfectly possible that person genuinely saw it as that. Eyewitnesses in chaotic situations are inherently untrustworthy and prone to misinterpret things and even create false memories when questioned. Especially if it was someone that, naively, still trusted in cops for some reason, it’s easy for the mind to create some assumed aggression by the victim, because only that way their worldview can remain intact (“a police officer wouldn’t have been that brutal without good cause” as an assumption, basically.)
Still, I agree, it is wild. Especially since even the bastard assaulting the driver here didn’t claim that. And I agree, it is also very much possible it was an overzealous fascist that just wanted to cover for the cops in a way more zealous than the cops themselves by consciously lying.