I think your last two paragraphs disproved your claim in the second. Yes, it is hard to place a player like that on a hand, and in that case it is difficult to play exactly correctly against his particular hand. But we never play against a particular hand anyway. Given a set of information (and you have fairly complete information on this player as an example), we are only informed of a probability distribution of the hands an opponent can hold. Knowing that a player uniformly holds any possible hand is great. It makes it easy to have very good expectation against him. Of course there is variance, but the correct play is ridiculously easy to find (generally just aggressive with strong hands, get out with very weak). And the fact that he busts 20/21 times demonstrates that he is free money at the table.
EDIT: And I don't mean to pick on your post. I just wanted to emphasize that poker inherently has variance, but that we should make decisions facing this variance to maximize the expected value of our result. Even in cases where there is a great deal of uncertainty (player can have any two cards for Christ's sake), we can secure a great deal of expectancy. How does this relate to far more imprecise terms such as "skill" and "luck" I don't really know. Who gives a shit? We should just understand the game as it is, and subjective terms like "luck" really aren't that relevant.
Poker is simply a process with a mean and standard deviation, maybe even some skew and kurtosis. It doesn't need to be treated as anything different. Why aren't people asking the same thing about investing in your 401k? It has a mean and standard deviation underlying it as well.