Greg McElroy had some strong words about it.
http://www.al.com/sports/index.ssf/2016/02/greg_mcelroy_says_cam_newton_q.html
"What I have issues with is the way he did not jump on the fumble after he dropped the ball -- and I know he was getting beat up all game -- but he jumped away from the ball when the ball's on the ground. I have never not one time in my life seen a player do that, especially a quarterback. And you know what? His teammates will look at him a little different after that, especially his teammates on the defensive side of the football."
"You can say what you want. The postgame press conference didn't bother me -- it really didn't -- because I think the media has a certain level of self-importance, especially when it comes to the Super Bowl. But I have big issues with the way he did not jump on the football."
"...It has everything to do with the fact that I think he quit on his team, and it was most evident by the way he did not jump on the football."