Yes, the slap was unnecessary and two wrongs don't make a right. But my focus wasn't to defend Will, but more so my focus was on the "triggering" effects of this type of comedy and how it can be hurtful. I think it is a part of the conversation many people are missing. Will was wrong, but the number of people who undermine being ridicule for a medical condition in a room full of your peers is amazing.
Yes, he may have laughed it off until he saw it hurt her. That causes a different reaction in some people. I learned one day in junior high, everything isn't funny. One of my classmates made a joke about a female in our class. It was funny to us, we laughed. But when I saw the look on her face I stopped laughing. Asked everyone else to stop as well. No I didn't slap anyone but you can laugh at something until you see the pain on someone else's face. Will's response wasn't the right one, but if you read the first chapter of his book. About how he saw himself a coward for not taking up for his mother when she was abused by his father. It puts some things into context.