This certainly differs from my mom's advice, which is essentially to be a member of at least one "average" peer group, in order to remain grounded in reality.

Your mom's advice only makes sense if your goal is to be average, because being a member of said group will make it difficult to do any better than average.

It's also an example of status-quo bias, because she's defining "reality" as whatever "average" people believe... but the type of people she considers "average" is itself determined by her pre-existing beliefs.

In other words, if you taboo "average", you find that the advice is really saying, "don't change, because you won't fit in with my group any more"!

(That is, it's exactly what we'd expect someone faced with a changing ally would say.)

Her idea is that if you abandon your current groups and join some other one, you'll begin to think like them whether their ideas are right or not.

I said "seek out peer groups in which their desired/target behaviors are normal".

In other words, the presupposition is that you've already come to the conclusion that you want to have those beliefs or behaviors, because you evaluated them before choosing to participate in the group in question.

I think it would take more evidence than you've given to promote this from plausible to probable.

But it nonetheless beats the crap out of the article's hypothesis, which posits an entirely new piece of machinery, rather than falling naturally out of existing theory (i.e humans are motivated by status and alliances, behavior signals likely alliances or changes of alliance, etc.).

AFAICT, nothing I've said in the explanation proposes any new instincts, machinery, or inclinations that aren't already textbook ev. psych. IOW, based on what we know so far, my explanation should be what we should predict even if we didn't already know people did this sort of thing.