That's a fair argument, I suppose. Personally, I've become quite fed up with the whole concept of lists and rankings when it comes to movies (although that doesn't stop me from creating them myself).
I think if Corliss' list had been simply a list of his ten favourites of the year, without numerical weight, then the comments for "Killer of Sheep" would be appropriate. The fact that he has it as #3, then goes on to say that it is the "finest film by a black director" does lead on to the (logical) conclusion that he believes "The Lives of Others" is better than any film ever made by a black director. This conclusion may not be what Corliss intended (if so, then it is indeed a head-slapper, and your lament "Who edits this stuff?" is warranted), or it may be Corliss' honest opinion, in which case a questioning of Corliss' taste is in order, not snide sarcasm. We always disagree with lists (how Reverse Shot's editors could come to the conclusion that the pale Scorsese retread "The Departed" was a better film than the visionary "Children of Men" is beyond me, for example, but I wouldn't question Reverse Shot's overall taste because of it). My point was that Corliss is probably one of the few mainstream critics who are promoting "Killer of Sheep", and for that I think he deserves praise, not scorn. Corliss' error (which may be a racist one, although I don't believe it is) was in distinguishing films by black directors from every other film, thus provoking the anger that has ensued here.
P.S. If you're going to take Corliss to task for anything, follow the lead of Evan (another poster here), who brilliantly dissected the contradictions in Corliss' article "Do Critics Know Anything?". Here Corliss seems to be playing both sides against the middle, praising the art films that spoke directly to him while at the same time lamenting the fact that many critics awards are going to films that haven't set the box office world on fire.