I think in his attempt to be contrarian, he's deliberately understating the many positive effects shown in many studies. For example, he mentiones Jennifer Bartz, who has found that oxytocin's effect is influenced by one's mindset. He doesn't mention that she's also found that oxytocin improved the ability of people with autism spectrum disorder to pick up on the emotional content of speech -- effects that lasted more than a week.
In many ways, oxytocin epitomises what happens when enthusiasm, salesmanship, and optimism runs ahead of evidence and careful experimentation. The true moral of the moral molecule may be that ideas that are too cleanly packaged are probably just fragments.
Oxytocin hype is building, and people are turning to the internet to buy oxytocin products because we are a society in desperate need of better connection. But I wonder why people are so excited (relieved?) to hear that better bonding isn't possible.