It&#x27;s not entirely an ad hominem.  The original claim contains an implicit appeal to authority in citing the link to the blog.  Saying that the authority cited is not actually a valid authority (due to a known bias) is not quite the same as ad hominem.<p>We resort to reputation to calibrate the burden of proof.  If the source cited is not a valid authority, that doesn&#x27;t make them wrong, but it does make it harder for them to establish a claim that merits rebuttal.