Into the fray......
What was the material? Expand a little more so we can acurately judge. I may be in total agreement with you if I saw the comic. Since you brought out the lynching reference, she must have been joking about how people died. Was she mocking the dead? The families of the dead? Saying something about a good job by the terrorists? What was so offensive about it?
There are 9/11 jokes done by many comediens, not just black and female ones. 9/11 humor is passed on TV, most recently I saw Dave Letterman and Jay Leno. One joke involved the battle over the new building that should be erected. Pretty funny too. Mario Cantone does a routine about Osama Bin Laden that is hilarious. And was doimg it at a comedy club in downtown New York just weeks after the attack. Lots of comedien's humor falls in around the retaliation, killing of the terrs, methodology of killing and insulting/belittling the culture which, unfortunately, those people came from. Insulting the Arab/Muslim culture is pretty offensive. No one's hopping on that bandwagon.
I don't know what was said but the simple fact is that humor can be part of a healing process.
Before you jump, like Frank Squid who was there, I spent two days in the rubble pile, where tower 2 used to stand in front of FDNY Truck 10 Ladder 10. On marine from my unit was a fire fighter on Thruck 10 and was killed in the collapse.
There's no honor in mocking the dead or anyhting funny about the incident itself but many popular comediens(including those on SNL) have found plenty of humor after the horror and made us feel better.
Sherm