Putting Ritzenheim in 2nd makes sense given the stated LRC premise: "Whose 5K season would you rather have?" I agree, I'd rather have an AR than 8th at WC, 1st at USAs, and sub-13:00 (but it's close--that US Championship means something; so does being in the hunt with 300 to go in a WC).
However, it's a different story if the premise is: "Who was the better 5K runner in 2009? Who would beat who head-to-head more times than not?" With this criteria, I think Tegenkamp has to be 2nd. (Ritz's AR race was more conducive to a fast time than Tegenkamp's 12:58 race.) Head to head, most people would say that Tegenkamp was more likely to have beaten Ritzenheim over 5000 in 2009 than the other way around.
Of course, it's LRC prerogative to set any criteria they want for rankings. And these questions are largely subjective and really just good fodder for discussion. Nobody should be bent out of shape about it--both Tegenkamp and Ritzenheim had really good years. But if it were me, I would base the rankings on who I thought was better at the distance, not who had a more exciting year.