Don't talk like a Californian eh?... Unless his interviews involve people telling him, a "dude", how the surf is "up" and how "radical" their new product is, I'm not really sure what he's talking about.
The writer is from Ireland. What does someone from Ireland think someone from California sounds like? I suspect they think a "California accent" is pretty close to the "non-regional dialect" that U.S. newscasters use.
I'm not sure this is what he's getting at, but my first impression of California is that everyone (or maybe just everyone in tech) talks fast. I'm Irish-born, so maybe I'm correct.
I think the point is "Be yourself. Don't try and use phrases that other people in the area or industry use simply because they use them."