The criticism invoked “anyone with serious experience with schizophrenia”, implying the author of the article is not such a one. Citing the author’s experience is a perfectly valid rebuttal to that implication. It’s not an argument from authority, but about it.
I'm not trying to say that that should strongly increase the probability he's correct. I just think it's useful context, because the parent is potentially implying that the author is naively falling for common misconceptions ("following the conventional tack") rather than staking a deliberated claim. Or they might not be implying it but someone could come away with that conclusion.
I mean, on one hand you have a professional psychiatrist who has treated many people for the disorder we're talking about, and on the other, we have a rando on HN who hasn't presented any credentials.
Not saying the latter person is automatically wrong, but I think if you're going to argue against something said by someone who is a subject matter expert, the bar is a bit higher.