[BearGoesChirp]

>Does this kind of nitpicking actually invalidate the argument?

It does if there are enough nitpicks showing that natural behaviors are becoming more accepted because they are natural. That isn't to say they are acceptable, but they are more accepted. And this doesn't have to be true of all behaviors, because there are many factors at play. It is even possible there could be a trend where behaviors are becoming more acceptable because they are natural even if all behaviors were becoming less acceptable, if there was another stronger force acting to make all behaviors less acceptable.

But if we want to get to the actual argument first presented, we would have to realize that comparing it to murder, adultery, or sexual assault is a strawman to begin with. The OP wasn't defending going around and murdering people who didn't look like you. They were saying that millions of years of evolution will influence our behaviors in small ways. It would be compared to other preferences, such as preferences in intimate partners. So, is wanting to have a specific gender, race, etc. in an intimate partner wrong? Is it socially unacceptable?

[emodendroket]

This is a philosophical question as much as anything else, but I believe that, whether we are successful in perceiving it or not, there is such a thing as objective right and wrong as distinct from social acceptability. I'm hesitant to say anything about how people should pick romantic partners, but it seems to me as though that is actually rather considerably narrowing the scope of what we're talking about. I do think it is wrong to intentionally seek to form an ethnically homogenous group of friends and associates.