They've failed to analyze the merits of the article sufficiently. They are, in fact, committing the "ad hominem" error -- they see what appears superficially to

They've failed to analyze the merits of the article sufficiently. They are, in fact, committing the "ad hominem" error -- they see what appears superficially to be a trustworthy news site, and they believe it unquestioningly, based on the supposed authority of the source, rather than independently evaluating the claims being made.