As a fellow Finn, I agree that our country is probably much more blunt and direct than the impression I get how the US works. That's also the way I like it, and I think you have gone way too far in the US in this politeness thing.

However, Finland is culturally quite homogeneous, so I think the reason behind the bluntness is not what you suggest it may be.

For a Finn, I think Linus is on the blunt side, but he's not an extreme case. In fact, I'd argue he's not an extreme case even among non-Finns; it's just that most people only hear about his rants.

Also, I find that Linus is somewhat quick to judge things, and often his reactions are based on a misunderstanding of the facts.