Agree.
There is no "live" television. Like radio, television has a delay so the director (and only the director) can cut the feed at anytime when things like this happen so it doesn't make it on the air. So, maybe the director was caught off guard as he didn't know what Will was going to do, but after the slap why do they have a camera on Will Smith as he shouts profanity, not once but twice. Something doesn't smell right about all of this from a TV production standpoint.
Don't invite Chris Rock, Rick Gervais, and a thousand of other comedians to host the show if you're worried that someone might take offense to a joke.