I don't rule out anything with fanatics anymore. I was thinking more on the lines of a frustrated narcissistic incel who felt that one or more of the victims humiliated him and he retaliated. This has the feeling of something very personal. It's as if he thought as he stabbed them, "You're not so cool now, are you?"
He was a hardcore liberal who are mental to begin with. You throw in the lockdowns, masks and jabs and you make them act out. Politics is a real possibility and will be hidden completely.