What is the route of administration? A peptide hormone like that will not be orally bioavailable, and even when injected IV I doubt much of it gets across the blood-brain barrier. Maybe it’s something like the DDAVP nasal spray (http://www.rxlist.com/cgi/generic/ddavp-spray.htm), which differs by only a few amino acids, but even then I don’t know how good the brain penetration would be. That’s even ignoring the fact that any peptide neuromodulator will have proteases waiting to cut it up as soon as it gets near the synapse.
Even if all the delivery issues could be sorted out, I somehow suspect that some of the variability in social behavior may be due not to the hormone itself, but due to its receptors. We already know about the DRD4 receptor having an effect on personality. Also, if I remember rightly, there was some study on voles that linked mating patterns to the expression pattern of one of the ADH receptors. If something similar is going on in some people, then adding hormone will not change the regional specificity of activation, only amplify the magnitude.
If it works for some people, great, but I wouldn’t bet on it.
From the article: ‘What’s more, it is a very safe product that does not have any side effects and is not addictive.‘
Similar predictions were made about morphine and heroin when they first came on the market. I would lay heavy odds that if an effective delivery mechanism for oxytocin were devised, some people would become addicted to it.