zlacker

Ad hom is use of an irrelevant characteristic to impeach a witness or malign a viewpoint.

"You wear funny hats so you're not a credible expert on waffle irons" would be an ad hominem.[1]

Noting the reputation and past history of a speaker or source, or noting well-known rhetorical red flags (http://classics.mit.edu/Aristotle/sophist_refut.1.1.html) is what we'd now call a strong Bayesian prior. It's not a proof that a source, speaker, document, or publication is wrong, but it's a fairly strong grounds for suspecting that might be the case.

https://www.thoughtco.com/ad-hominem-fallacy-1689062

And in a world in which asymmetric costs favour bullshit, it's a useful and often necessary approach.

https://en.wikipedia.org/wiki/Brandolini's_law

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Notes:

1. In practice, "funny hats" might well be references to non-Western clothing (see The Little Prince for a fictional illustration), or speech, or gender, or religous affiliation (religious exclusion was common in top US universities well into the 1970s). It's still practiced in many regards. What this ignores is the specific capabilities or validity of claims or methods.

>>dredmo+(OP)
That is not a correct use of ad hominem. Translated literally, it is "against the person," which is what an ad hominem attack is -- an argument against the bearer of the idea that does not argue against the idea itself.

An argument against the idea was almost presented (anonymous staffers whose quotes cannot be independently verified) but was let down by its conclusion (it falls to the reputation.)

There was nothing in OP's argument that contradicted the claims that were made other than those that go against the reputation of the author, ergo even if they are valid, they are definitely _ad hominem_.

>>bmelto+8i
This would be a more interesting rebuttal if the story itself didn't stake the validity of these arguments on the identities of the people making them. Given that it's based in part on an appeal to the authority of, e.g., anonymous NIH scientists (in which group? with what kind of tenure?), pointing out the anonymity of the sources is not at all fallacious.