Buchanan has a history of being anti-Semitic. Why shouldn't sink bring that relevant fact up?
Because the argument made by Buchanan in the article can be analyzed on its own merits, without regard for any personal flaws Buchanan might have. If Buchanan's position were "critics of Trump are wrong because they are Jews", then anti-Semitic tendencies in Buchanan would be relevant. But that is not Buchanan's argument, and whether or not someone is Jewish, or biased against Jews, is not relevant to this discussion.
Buchanan makes, in my opinion, a fair argument that the judiciary is not immune to challenge, and that race has already been injected into questions of judicial fairness; the "wise Latina woman" is Exhibit A. Although the left has unapologetically made race a consideration in choosing judges and justices, Conservatives have believed for many years that race is not a valid consideration; the argument against Trump's position, and against Buchanan's defense, is that Conservatives simply do not accept that race is part of the discussion and we will not jettison that long-held belief now just to defend Trump. Democrats are hypocrites for calling Trump a racist in this context, Conservatives (if we remain true to our values) are on entirely solid ground in arguing that at least Trump's argument is racist on its face.
Apart from the principle I'm trying to articulate, I also find persuasive the purely practical argument that Trump's attorneys have not filed a motion to have the judge recused, and in fact have praised the judge for "doing his job." If Trump actually "has a case", then he should get lawyers who are willing to fight that case, because his current lawyers seem unwilling to do so.
If a stronger connection is made between the judge's La Raza legal association and the policies of the National Council of La Raza, then there might be a defensible argument for the judge's recusal on grounds of that association. But his race or ethnicity is simply not a basis for questioning his ability to preside fairly.
I believe Trump's position is a cynical appeal to race, or perhaps ethnicity, in the pursuit of a public relations advantage, and I believe some of the arguments against Trump on this issue are themselves flawed. But there is a solid, consistent ground for arguing against Trump, and against Buchanan's defense of Trump, consistent with beliefs Conservatives have held for years.
