The booth isn’t necessarily the line.. he could have technically been on Canadian soil. Also, is there really a difference if the border guard asked him to pull in after he had the conversation? In fact it probably saved him time since he was waiting anyway. They were doing him a polite favour! How Canadian!
For real though that sucks but man cover those damn LED bars. I give my buddies crap about it too. Such an easy thing to avoid getting ticketed for.