Nice one mate, theres to many idiots out there who think there hard as nails when there couped up in their cars abusing other road users, They diserve to be knocked down a peg or too. Ill always check someone out before I give any gestures etc.
Also I prob would have pulled outta his way, its his responsability to decide whether he obeys traffic laws, you never know he may have had his pregnant wife giving birth in the passenger seat or could have just been racing to tescos for some more fake tan