It usually takes two to road rage. She likely wasn’t brake-jacked for no reason.
It doesn't sound like she was merely being passive, if she were, she would merely have slowed down and when he braked she would have braked also, instead she totally wrecks and is ejected from the vehicle, something is wrong with her driving.
Road rage does happen for no reason
You can set off a nut for absolutely no rational reason
Going too slow, trying to pass, pulling into his traffic lane, blowing your horn, or just for looking sideways
Ever try to pass someone on a country road at night? Think you deserve death for that?
One night some years ago we pulled out to pass another driver and this enraged him, he repeatedly sped up, slowed down, wouldn’t let us pass, wouldn’t let us not pass, and for several wracking minutes refused to let our family back into the lane, even though a truck was coming at us head on
Luckily we braked and slipped in behind him just as the truck went by, then he played the “hit the brakes” routine
Then the nut kept going, is still out there as far as anyone could tell
Sometimes when there is a fatal accident for no known cause I wonder if someone caused it out of rage