It doesn't have to follow as the two points are, or at least can be, independent of each other. You racially abuse someone who is fit and able (i.e. someone who can choose whether to physically lash out) and your rights are forfeit - what the law says is irrelevant, as we already know hitting anybody under any circumstance except self-defence is wrong in a court of law. The reality is, in real life, people will decide in a split-second what they will do as a victim and the range of reaction can go from very little, to life-threatening dependent on who those offensive words are said to and their actual capability to do something physical about it.
I'm pretty sure there isn't a sane person who thinks if you racially abuse 100 physically capable men, the likelihood of physical confrontation wouldn't be extremely high (and less than acceptable in a court of law) within that number and most people wouldn't be surprised at that unless they live in a Utopian bubble.
As numerous comments in here have shown, the moment people thought the incident was racial in tone, they sided with the victim and shrugged at the outcome being what it was, but outside of it being racial, there are comments - only then - saying what Evra did isn't right. It's transferable to real life and if you're in a place where racism isn't condoned, and someone racially abuses someone else (who is capable of physical retaliation), few in a crowd would be surprised by the escalation, and even fewer would rush to the aid of the initial abuser if he got twatted - in fact, and I've seen it countless times, he's most likely to be jeered and his victim cheered.
The idealism of 'violence is wrong' in a racial situation mostly comes from those who have no idea what it's like to be on the receiving end of it; the lack of empathy or the inability to identify or relate to the victim or his retaliation go hand in hand.
Amongst those who are victims of racial abuse, are capable, but opt not to do anything (walk away or laugh it off etc.) there is a separate debate to be had.