That air gap is being created by Netflix. Why would they separate the sites and businesses so distinctly if their intention weren't to create an air gap?
You really think that the respective sites will have no integration? Not a single-sign-on user account? Not an "Available on Netflix" link? Why? It makes business sense for both units and it doesn't impede any of the objectives of the spinoff.
"A negative of the renaming and separation is that the Qwikster.com and Netflix.com websites will not be integrated."
http://blog.netflix.com/2011/09/explanation-and-some-reflect...