Guy sounds like a jackass. Most people don't freak out about tabs being used for navigation compared to alternate views of the same content. I find it ironic that he'd say "correctly uses tabs" as opposed to "incorrectly". There is no prescribed correct or incorrect ways to structure a site. In fact, every major evolution of design starts with a site which is "noncompliant" but people like it anyway.

There's numerous guidelines on how to set up a site, however, if you want to follow industry standards. I'd avoid saying what's "correct" or "incorrect" however, since design is primarily and fundamentally a subjective thing.