For everyone dismissing you on the basis of an ad hominem attack, here is the first paragraph from Wikipedia. In particular, notice the second sentence:
An ad hominem (Latin: "to the man"), also known as argumentum ad hominem, is an attempt to link the validity of a premise to a characteristic or belief of the person advocating the premise.[1] The ad hominem is a classic logical fallacy,[2] but it is not always fallacious; in some instances, questions of personal conduct, character, motives, etc., are legitimate and relevant to the issue.
Ad hominem is not fallacious when a person is attempting to argue by authority. The wikipedia article gives this example:
Conflict of Interest: Where a source seeks to convince by a claim of authority or by personal observation, identification of conflicts of interest are not ad hominem...
Steve Sailer is not arguing from a authority, so in this case the ad hominem is a logical fallacy.
It's often useful to read more than the first paragraph of a wikipedia article.
You've pulled one sentence out of a subsection and attempted to use it as a definition of the only way for an ad hominem to not be fallacious.
You've quoted from "Conflict of Interest" under the "Circumstantial" fallacy section. Under said section, it is clearly stated, "The circumstantial fallacy only applies where the source taking a position is only making a logical argument from premises that are generally accepted."
Regardless, I rescind my earlier comment because michaelchisari's statement was simply not an ad hominem attack. He wrote:
With such a clear, ideological bias, I would hope that people here would know better than to accept their conclusions without some serious corroboration or fact-checking.
At no point does he argue that what was said is false, only that readers should be skeptical due to evidence of bias and check their facts.
> It's often useful to read more than the first paragraph of a wikipedia article.
Can you name another circumstance under which ad hominem is not fallacious?
As far as I'm aware, disputing an argument from authority is the only non-fallacious use of ad hominem. That's because an argument from authority is dependent on the character of the speaker, and attacking the speaker therefore can debunk the authority.
An ad hominem (Latin: "to the man"), also known as argumentum ad hominem, is an attempt to link the validity of a premise to a characteristic or belief of the person advocating the premise.[1] The ad hominem is a classic logical fallacy,[2] but it is not always fallacious; in some instances, questions of personal conduct, character, motives, etc., are legitimate and relevant to the issue.