Telling them that their concerns about the game are not warranted, because they don't play "right", is rude to the point of arrogance, and I just plain don't like it.
Scott, I think that you're taking Leo's comment a bit too seriously. I can't speak with any certainty on Leo's exact intent, but the way I read it was that given that the game's balance is largely dependent on player skill levels, and the disparity of those skill levels between one another, as is often evidenced in the various AARs, it is difficult to balance a game with so many uncertain data points, as measured in game results, when so many of them are from obvious skill mismatches.
Philosophically speaking, as long as two players are having fun, you can't say that one, or both of them, is playing "wrong". However, if you're measuring success by any type of objective criteria, such as where the lines lie at point X in the game, and the relative OOB strengths of the antagonists, then you can, with some reservations, say whether a player is playing well, or not. Whether you feel it's rude, depends, I suppose, on how it is said, and in what context. In Leo's case, I don't think it was meant out of any malice, or rudeness. Rather, it was a simple observation that some players are not showing a high level of skill, at this stage.