I think the commenter is trying to make two points here: autism is a genetic/developmental thing. The idea that it is acquired by some GI aberration, or maybe vaccines, is a solidly refuted hypothesis. A lot of harm has been done by snake oil salesmen selling enemas, chelation therapy, etc to desperate parents of individuals with autism. Secondly, they are asserting that ASD is only called a disease because parts of the neurodivergent spectrum of humanity have been pathologized by our society. Compare it to homosexuality: also once called a disease and also likely tied to genetic and/or developmental processes, but no longer stigmatized by that medical designation.