I've just identified something else that was nagging at me about this post: the irony of the author of this post making an argument that closely parallels an argument some thoughtful conservatives make against condoning alternative lifestyles like polyamory.
The essence of that argument is that humans are not sufficiently intelligent, rational or self-controlled to deal with the freedom to pursue their own happiness without the structure and limits imposed by evolved cultural and social norms that keep their baser instincts in check. That cultural norms exist for a reason (a kind of cultural selection for societies with norms that give them a competitive advantage) and that it is dangerous to mess with traditional norms when we don't fully understand why they exist.
I don't really subscribe to the conservative argument (though I have more sympathy for it than the argument made in this post) but it takes a similar form to this argument when it suggests that some things are too dangerous for mere humans to meddle with.
While there are some superficial parallels, I don't think the two cases are actually very similar.
Humans don't have a polyamory-bias; if the scientific consensus on neurotransmitters like oxytocin and vasopressin is accurate, it's quite the opposite. Deliberate action in defiance of bias is not dangerous. There's no back door for evolution to exploit.
A few examples (in approximately increasing order of controversy):
If you proceed anyway...