The greatest self-contradiction in cinema?

My son was watching Revenge of the Sith the other day, and I caught a few moments of it. It reminded me how the following exclamation of Obi-wan Kenobi stunned me:

Only a Sith Lord deals in absolutes!

My jaw dropped even when hearing it the third time. In every Star Wars film, it is the Jedi who deal in absolutes. The Sith deal in selfishness and "points of view", far from the absolutes of good or evil. Palpatine's seduction of Skywalker, using the tale of Darth Plagueis, illustrated this brilliantly.

Indeed, a few minutes later, Obi-wan Kenobi reverts to Jedi form:

Anakin, Chancellor Palpatine is evil!

That is an absolute, and Anakin reverts to Sith form:

From my point of view, the Jedi are evil.

Kenobi's reply is splendid:

Well then, you are lost.

But isn't it a little late for absolutes of this sort? Who can blame Anakin for being lost, Kenobi can't figure out which side deals in absolutes?

I've wondered if Mr. Lucas deliberately placed this self-contradiction in order to highlight the moral degeneracy of the Jedi, that they deserved their near-extinction, or if the rumors are true that he was taking a shot at the current president. If so, it was not very effective, IMHO. I'd like to think that he meant that "only a Sith Lord deals in false dichotomies" and after grasping too long for the right word moved on; that would have been a very effective response, IMHO, and apt, too.

I guess I'll never know, and after such a glaring self-contradiction I no longer care. Ben Kenobi was my favorite character of the series, and still is to an extent. Alas, I am lost.