My personal opinion is that the 'fighting words' doctrine is bollocks*, however, that doesn't obviate your point. I suspect he wouldn't have reached that threshold for 'fighting words' although, by reputation, he is a complete arse, so may have done.
*I don't mean it doesn't exist over there, I just mean I think it shouldn't.
Fighting words alone don't really exist in law (anymore) in the US as a defense to assault. They can be a criminal act such as breach of peace if the words have a substantial likelihood of instigating or inciting violence and are not otherwise protected speech. They can also act as an element to constructive assault -- against which one could claim the justification of self defense.
For instance, I corral you at a restaurant table and start talking endlessly about the latest Paris Hilton scandal (or some other irritatingly boorish topic) while kind of physically blocking your exit. Society would expect a reasonably prudent and cautious person at the point of wanting to extract themself from the situation to interrupt, ask the person to leave, ask the person to move aside so you could leave yourself, ask the restaurant staff to remove the distraction, etc... It probably would not be judged reasonable to extract yourself using physical force as an initial response.
Let's say you were at the same restaurant but this time at you beloved sister's wake. I come up, similarly block your exit and prattle on about how your sister was a dirty whore who did not deserve the advantages she had in life or some similarly scandalous behavior. Society probably would judge someone so affected -- but otherwise reasonably prudent and cautious -- able to extract themself physically, having judged the behavior so outside the norm that with it comes a reasonable conclusion that the more kind of intermediate courses of action were not tolerable or unlikely to succeed considering the circumstance. That is, you wouldn't be expected to suffer further abuse in an attempt to leave peacefully.
There's some examples that sort of split the difference as well. I start talking loudly in public about my opinion of your beloved sister/mother/wife as a common whore. You decide to intervene physically. Your simple assault may be deemed unlawful and likewise my ability to claim justification against that assault may suffer the defect of provocation.
Even 150 years ago, fighting words weren't mere disagreements of opinion. They required the element of being a personal affront to honor which required a person to respond under the social
mores of the day, thus effectively preventing what would have been their ability to withdraw from or avoid the conflict.