What kind of conspiracy theory is this? Why does Facebook want to go to the expense and effort of building a useless profile of you?
Secondly, the profiles aren't 'useless'. They're highly valuable. Both for being able to present users with a targeted experience from day one & for controlling the internet-identity part of the online world. Which will surely only become more important with time, as more and more things from our lives move online.
He's implying that they aren't doing this for better ads or targeting. I'm not saying that "shadow profiles" don't exist, I'm saying that they do, and they're benign.