I think the author was writing mainly to an audience of English-speaking ex-pats who have no experience with Russian culture. I agree, a lot of his conjectures about why Russians smile less than Americans, or stand close, etc, are crap. I never thought it was "rooted in the oppressive Soviet past."
However, I have heard from other Americans before that they think Russians are "rude." I never thought Russians were rude personally, so I asked people why they made this observation and from what I can gather, it's just a cultural misunderstanding on the part of (mostly) Americans. Americans do not tend to be as direct as Russians are, and they will mistake directness for rudeness.
Americans and other English-language speakers seem more passive to me. For example, if they want a drink of water they will say, "Would you please get me a drink of water?" Whereas a Russian would probably just say "I need water" or "I want water."
I think sometimes we misunderstand each other precisely because of cultural differences. Americans say "I'm sorry" all the time and I've heard from lots of Russians that this makes us seem insincere, but in America it is considered proper and polite.
Generally, I think reading motives into the behavior of foreigners is a bad idea. What might be perceived as "rude" in one culture is honesty/directness in another, and what might be perceived as "insincere" in one culture is politeness/kindness in another.
I agree, the author is reaching a bit and sounds like yet another westerner trying too hard to psychoanalyze Russian behavior. I think a lot of the behaviors he is describing are not a direct result of Soviet times, but reach back far further than that and are not wrong or a sign of oppression but just cultural.