As far as I know, this is the first thread in which it has ever been pointed out that Omega doesn't need to be infallible or even close to infallible in order for the problem to work. [...] As far as I am concerned, a real and non-trivial improvement has been proposed to the statement of Newcomb's problem as a result of my so-called "discussion" posting.

I'll note here that the lesswrong wiki page on Newcomb's problem has a section which says the following:

Irrelevance of Omega's physical impossibility

Sometimes people dismiss Newcomb's problem because a being such as Omega is physically impossible. Actually, the possibility or impossibility of Omega is irrelevant. Consider a skilled human psychologist that can predict other humans' actions with, say, 65% accuracy. Now imagine they start running Newcomb trials with themselves as Omega."

Also this section wasn't recently added, it has been there since November 2010.

In short you're not the first person to introduce to us the idea of Omega being impossible.