I do agree that Lebron is not a dirty player. And in this situation, it seems that he didn't intentionally try to throw that elbow on Stewart. They are all jockeying for position and no one want's to give up and perhaps James is trying to regain control and accidentally throw the elbow to Stewart face. And as per report, he will be suspended one game without pay.
I guess some times intention doesn't matter in cases like this, James isn't and has never been dirty player (this being his first suspension and 2nd ejected over the course of his illustrious career would also corroborate that fact) It was pretty obvious that James was trying to apologize immediately even before Stewart stood up perhaps knowing the impact that the fist could have made, but the damage has been done already intentional or not. I'm sure Stewart would reflect on the replay seeing that James was sorry instantly and probably didn't mean for it to happen.