To each his own, but I wouldn't be celebrating someone writing books intended to piss off black people or the LGBT community either.
I guess nobody's getting death threats for still saying "blacklist" or "quantum supremacy", but people who are oversensitive enough to care deserve to get offended.
That said, I don't think we should encourage causing people offense. It's worth being aware that a person may get offended by harmless things because of mental illnesses like psychosis, so it's worth being sensitive to that.
Yes, you should be allowed to offend whoever you want in a free society.
But admiring people because of their intent to offend large groups of people is just weird.
But "like offending people" is not objective. The burden has to lie with offendee as well. Flat earthers might be offended by someone saying Earth is round, but that doesn't mean that person saying that likes offending flat earthers.
So it's just pure hypocrisy and pretending otherwise is silly.
This is a false framing. The person who wrote the post you originally replied to does not appear to be doing that; the comment praises Rushdie for saying uncomfortable things and challenging entrenched views, not for insulting people.
It may be (as as been suggested in these comments) that Rushdie was indeed trying to offend people, but even if that were the case, it does not mean that his supporters are celebrating him for that.
In fact, I feel it is fairly safe to say that, for most of his supporters in this matter, he is something of a MacGuffin: they support the position you concur with in your second paragraph, and he just happens to present a case where it is under significant threat. Opposition to terrorism (state-sponsored terrorism, no less) does not necessarily imply or depend on supporting the victim's position or all of their actions, any more than opposition of the death penalty is an endorsement of murder and its perpetrators.
Even people who have reservations about your second paragraph can see that Rushdie was not threatening anyone, directly or indirectly.
I kinda disagree with this. There are certain parts of the book that I don't think could be interpreted any way other than antagonization.
Reading the book, I felt like he even went out of his way to antagonize muslims. There were parts when I had to ask myself, "Is xyz really essential to the plot?"
I'm not muslim, fwiw. And this goes without saying, but no one should be persecuted for what they write.
Being a voluntary member of an organization is a choice.
Someone tried to attack Dave Chapelle on stage just a few weeks ago for making jokes about trans. What rock are you living under?