Why would it make sense? Would any Mac user use IE? How many Windows users use Safari? Not many I'd wager.
If IE becomes really good, it should be judged on its own merit and maybe some people on the Mac platform would want to use it.
I dislike Microsoft as much as the next guy, but I know that when there's healthy competition on a platform, everybody wins. I'd love to see the IE guys try to make a better browser than others, and not just on windows.