One can be "non-fake" without having to be a complete asshole. Being civil and mature is more about being able to maintain a neutral ground for discourse and cooperation. Being able to resolve differences and conflicts in a calm, rational, and mature manner is not being fake; it's being an adult. Being completely unwilling to do so and trying to justify such unwillingness just being a big, overgrown baby who wants to always have his way.
I did a quick google of the whole Management by perkele style of the Finnish. That style is simply to be decisive and to get on with just doing something (not wasting time), not being a complete egotistic jackass to all around you. One can be direct, truthful, and to the point without being a douchebag. So, I don't buy the whole "It's my culture" thing. That's just a bullshit excuse.
ADDENDUM: Some of you praising Linus, if any one of you actually found yourselves in a real personal situation in which this was how people treated each other, I guarantee most of you would either leave or find yourselves coming to fisticuffs with the person. Would you really want to be in an environment in real-life in which people treated each other the same way as folks treat each other on the Internet and in online games? Think for a moment how that would turn out.
No, sorry, Linus is just wrong. He's simply being brave behind a keyboard; otherwise, he better know how to physically defend himself, because I could see him getting beat-up a lot in public for being rude, in exactly this manner, to just the wrong person. In fact, I guarantee that he probably exercises exactly the kind of "fake politeness" he claims to hate so much if he ever finds himself in a situation in which not doing so could get one physically very hurt, or even dead, but even more so where being an asshole means he won't get what he wants. Nope, sorry, I just don't buy into this kind of bullshit rationalization.
At least just admit that being an asshole to others just makes you feel more empowered. I'd be willing to believe that.