Those instructions apply to 3.2 (and I'm including the compat patches there in the next patch). I've checked the 3.9 code though and it's essentially the same as Ubuntu's 3.8 kernel. Do you have AppArmor enabled?
I can't try it at the moment, but it's been going on for ages. Way before 3.9. I've been using Grsecurity since at least 3.2 and it's been this way since day one.
But my results seem to be the same as the topic creator at serverfault.com, if the patch fixes it for him I'd imagine it fixes it for me too, right?