The official rule book contains at Rule 12, Section 2, Article 13(8) a phrase that possibly creates a loophole for a helmet-to-helmet hit. If the quarterback is “attempting to advance the ball as a runner,” all protections for the passer apparently go away.
Harrison’s hit on McCoy could fall into gray area of rulebook | ProFootballTalk
Go ahead you guys were saying?
I've already posted the rules directly from NFL. If you chose not to read or understand them, well, there's nothing I can do to change that. Have a lovely weekend. I'm out.