Professor Brandon, Serious and mature discussion of an issue does not involve implying that one's opponents are "stupid," let alone by committing a gross logical fallacy (the distributive fallacy of composition ) as you do in your seriously intentioned "joke."
The graver fallacy that you're committing here is "red herring." The subject of this debate is not academic indoctrination (that is merely a potential negative consequence of what is being discussed), but diversity in the faculty being regarded as a -inherently- good thing for the academy, where -racial- diversity is seen to be a positive goal to be achieved while -intellectual- diversity is eschewed.* In its most gross and offensive form, this attitude assumes that diversity of skin color EQUALS diversity of thought, which is a patently racist attitude. Happily, your fallacious statements put you out of that class of arguers, since, for you, diversity of thought is "stupid" for "white" academics as well.
Finally, your comparison of the sciences and the humanities is fallacious on categorical grounds. For the sake of argument, I'll consider your red herring. While ideological indoctrination is not unknown in science (as your erstwhile colleagues in the English Department used to "bloviate" about), the subject matter of mathematics and its method is not a subject of debate -within its own discipline.- A putative Lysenko of mathematics would be put down by his own leftist "allies" as a destructive influence.
The same is not true in those disciplines which deal with the humanities, where discussions of values and political and philosophical positions have precedence. It is there that a diversity of views in the faculty about the pertinent aspects of the disciplines would have prima facie desirability. This is the substantive point at issue.
* It has to be noted here that Horowitz and company are -not- arguing that since there is a lack of intellectual diversity on campus, there should be no racial diversity either. Rather, their argument is that the primary purpose of the academy is to inculcate ideas and critical thinking skills, and thus intellectual diversity exemplified by qualified faculty members of all races, creeds and beliefs should be the aim of academia.
Correction to my original post there, I am currently not in grad school, but I plan to return this fall.