You are not asked to update your belief about the answer being "even" upon observing Omega (in any sense of "knowledge" of those discussed in the post). You knew that the other possibility existed all along, you don't need Omega to see that. You are asked to decide what to do in the counterfactual.

Consider uncertainty about when Omega visits you part of the problem statement, but clearly if a tricky condition such as "it only visits you when your decision will make it worse for you" was assumed, it would be stated.