[aspasia]

Diversity can also be a strength, so there are kinds of diversity.

It depends on whether it is divergent or convergent.

Adam's Smith's principle of the division of labor is a diversity of parts to a whole.

[semantic]

Continuing to conflate division and diversity is going to cause you logical problems similar to how you just demonstrated. Armies and armed forces are highly unified, even though they are also highly stratified with discrete duties divided among a multitude of different criteria. So to ant colonies - tremendously unified and on hair trigger alert to aggressively respond to any other organism not part of the queen's family.

Biological diversity doesn't mean nor imply diversity within species and/or groups. Rather, it means diversity within every conceivable environmental niche which in turn is the primary driver of speciation. That is, the very definition of in/out groups ie those that can no longer reproduce.

Regardless of these mundane semantics, the real issue - as I pointed out above - is the ability to identify enemy tactics and techniques. The wholesale brainwashing and gas lighting of entire populations is the real marvel. I would think prospective academics should study that phenomenon, rather than the obvious refutation of the ridiculous "diversity is strength" slogan.