Totally agree with you with the gatekeeping. This is an informal conversation, and you’re just a random person from the internet. There’s no standard you must be held to, and people shouldn’t take what you say to be some statement of empirical fact.
Let's posit that I'm completely batshit insane and deluded and imagining that I have a genetic disorder and imagining that I'm getting better when doctors say that cannot be done. Let's assume the critics and haters are correct in that regard.
It has zero bearing on whether or not fasting would help with HIV. Even if you sincerely believe that I'm completely nuts, you could have a constructive good faith discussion with me about the medical details of how HIV works and whether or not fasting has any reasonable hope of being useful treatment for that specific condition.
And if I were nuts, talking to me about exactly how HIV works without being ugly and dismissive might make me less crazy and help find my way back from insanity to some kind of healthy relationship to reality whereas the kind of engagement I all too often get on medical topics is crazy making.