First , I want to state that, it is my position the NFL should and has the right to protect players from some of the inevitable dangers of being a professional football player...for instance players are required to be @ least 21 for all practical purposes..The restriction to enter says that a player must be at least three years removed from the end of high school, or that he must have completed at least three years of college..players are required to wear official NFL equipment that the league and teams provide...thus everyone has access to the necessary equipment to do their job, players are required to be deemed physically able to participate in the game by their team's physician etc and so forth and which are reasonable expectations...hey the NFL has evolved over the years.
Yet, given all the necessary and reasonable steps that the NFL has taken to protect the players football is still the ultimate team contact sport, or at least it is for now, and contact means just that contact. When an offensive player is in the act of making a play and said player is advancing the football by definition it is the defensive player job to immediately cease their advancement, and if at all possible obtain possession of the football. James Harrison made every reasonable effort to do just that. Harrison's intent was not to injure Colt which he could more than likely done by going low at his legs or knees instead he made an effort to cease Colt's progress by targeting the center of his chest- which is a text book tackle- and an area of the body where it is reasonable to expect contact.
What more can you ask or want from a defensive, not defense less, player? If the offensive players moves or lowers their head to protect a part of their body during the nano second that the defensive player has to make a decision to do their "Job" who is at fault? The officials are so quick to throw the flag when a defensive player makes contact and that is physical contact, with an offensive players-especially the QB- the discrepancy is starting to become fictional.
It should be a reasonable expectation that when a defensive player makes a text book, and, yes, even a text book "Big Boy" play on an offensive player, including the QB, that the play will not result in a penalty or subsequent fine. Inevitably, players are going to have helmet to helmet contact and if the NFL wants to get this right they need consider that instance and that play and not the simple fact that there was helmet to helmet contact, or find some other form of contact or method that the defensive player can use that will result in the offensive player progress being stopped.
Then again, if all else fails the NFL can implement a new rule which can designate two hand touch only for certain players!! I wonder if this would be considered a reasonable expectation.