There's no proof he embellished.
Guy got his neck snapped around/"bell rung."
No one in their right mind is going to guess his hurt level in that situation and give him a penalty.
Just cause he played again soon after doesn't prove he wasn't hurt. Plenty of people get knocked out and get back out there in sports (especially before the concussion protocols).
If an intentional elbow to a players head isn't a 5, I don't know what is.