Are you saying INFJs don't commit suicide?
Well I didn't want to start a debate on suicide/Kurt's alleged suicide but I will try to convey my feelings clearly.
I'm sure anyone from any type can and would commit suicide, everyone is capable. I can only speak for myself and my personal life experiences. I don't think it would be easily/frequently done by INFJs based on my personal views on suicide and assuming I have developed those views as a result of my personality type. Maybe not all INFJs feel the same way as I but even in the lowest moments of desperation in my life, when I wanted my own pain to end, I thought about the pain it would cause others and that sentiment always prevailed. I cannot speak to everyone/for everyone that is an INFJ, and again, who knows how heroin would affect that mindset, but it is my personal opinion that Kurt Cobain did not kill himself and that is based upon more than his personality type. But again, none of us lived his life, so its only speculation. I do think that his personality type gives further evidence to my already established belief that he did not kill himself but perhaps that's only because I identify with him as an INFJ and I have established views on suicide whereby others > self.
My sentiment is that, as a mother and an INFJ, if Kurt is typed correctly, I would think that thoughts of his daughter would prevail before he would commit suicide. Regardless of the insurmountable pain you are in, your children's feelings and happiness comes first (and I know that's not a sentiment that's exclusive to INFJs, but certainly the weight of that life probably feels a little heavier especially when thinking about suicide). Also, if he was leaving Courtney and felt that she was crazy, he would not have left his daughter with her. If he had committed to killing himself, he would have done some things to ensure the future well being of his daughter, in my personal opinion. I don't think suicide is a spontaneous decision, an INFJ would take lightly. (again, Heroin is a factor here, and I don't know how that plays into his mindset, though most of the heroin addicts I know are not suicidal or want to die as far as I know.) Plus he had recent attempts at getting clean right before he died, someone who wants to die isn't going to bother with rehab.
But I said I was a little biased, not sure if you have seen Soaked in Bleach, I believe it's on Netflix.
Edited to Add: Of course anyone could make any argument they want (regarding Kurt Cobain), just giving my 2 cents.
I also don't want to come across as saying "suicide is selfish" which after reading over my post I see that that message might be conveyed. I do not think that way at all. I think many people who commit suicide see it as a means to an end (of pain). I'm sure in some cases it is well thought out and planned and in others it is more of a spontaneous decision. I empathize very deeply with those who feel they have no other option and only wish more people would recognize that others are struggling and may need help. Some people do not feel comfortable asking for help or feel that no one understands or cares, and I find that extremely heartbreaking. More than I can convey in words.