The fact that the culture isn't absolutely, consistently accepting is unfortunate, but it's much better than what came before.
I'm sure a bias exists, but it's subtle. It's the sort of thing that if you expect, you'll see more.
> They smile when the quirky and brilliant hacker wears pajamas and rollerblades to the office, but when they meet the coder in a suit, their polite expressions falter for a second.
Polite expressions faltering? That's the sort of thing you'll find if you're looking for it, whether it's there or not. A person wearing pajamas would have a larger effect in absolute terms; the difference is relative: a tech company would be more accepting of pajamas than you'd expect and less so of suits.