We have plenty of questions tagged with human-biology that have close relations to medicine: question about scar color, about effects of antibiotics intake etc. And as long as the question is about biological background of some medical facts -- it is perfectly on-topic and is answered duly.
The question you mean is something different. Unlike the examples above, where the main purpose of the question was (in my opinion) to get biological explanation for some medical facts, answering this question might be treated as prognosis for an existing health condition and/or can influence the decision about possible medical treatment (not necessarily by the person who asked this question, but rather by many others who might find it by mere searching). To me this clearly falls into the category "medical advice". And I don't want to jeopardize SE project with some law suit because of this.
I do understand that this might disappoint some people who are looking for a broader scientific review on some issue from medical biology, but the person provides two links to scientific medical publications in his answer -- this implies that he is capable of searching for this information on his own.
Sincerely speaking, I would even accept the question as an on-topic one if it were formulated a little less personally and more scientifically, something like: "Effects of sodium benzoate on animal or human fetuses?". This would allow answering this question from purely biological viewpoint without the danger that it looks like a medical advice (again, at least in search engine output) and provides enough information for the person who asks.