There is "incidental contact" and then there is what Williams did to that referee. Already down 33-10, the Packers were hit with a 15-yard penalty for that infraction by Williams. Clearly frustrated by being down 23 points and outgained by more than 400 yards, we can understand frustration. This is a much different Williams than the one we saw after he intercepted Matthew Stafford in the second quarter when the game was still close.
But a move like that doesn't just cost you yards, it'll likely cost Williams a lot of turkey.
Update: Williams claims it was an accident.