Genuine human error? Brainfart? Lapse of focus? It looked very weird, my reaction was why the fuck did he do that? But rationally he can be a dick but I can't see him intentionally trying to injure riders by causing a crash. How many has he been in? You just don't do that.
I'm no bike racer, but I do ride a bike. There's no way I'd use it to bludgeon another rider, because I'd know I am as likely to go down.