It is simply poor English,however you want to dress it up and nothing to do with colloquialism. You’re just deflecting. Furthermore,if you make an absolute statement ,which you repeat, "suicide is selfish " without qualification you can’t then invoke exceptions when that statement is challenged. Nor berate others for not assuming that in reality you did have exceptions ,but left them unsaid.
It appears that English lesson you sorely need should be supplemented by one in logic and clarity too.