Is it offensive to joke about John Hinckley Jr? Too soon or fair game?

I wrote a romantic comedy about failed presidential in John Hinckley Jr and a couple people who read it seemed P.O.ed. I know that the American public can be touchy about their political figures being shot, and really that's good. Very patriotic, but I've counted and I only refer to Reagan four times and it's way toward the end of the story. Two people stopped mid-way and stated plainly, "I'm not reading any more." So what's you're opinion? Would you joke about him?