In Arizona, lane splitting is specifically illegal. I'm paraphrasing, but "at no time shall two vehicles share a single lane." This idiot cager took enforcing that law just a little too far. My take is that if lane splitting were legal and drivers are aware of it, he wouldn't have had anything even slightly resembling cause. It looks like he'd still be pissed off and find another excuse, but at least there wouldn't be anything remotely close to legitimate.