@Mr.Sigma. No problem; I'm usually idle... you happened to catch me when I am here
In a nutshell, I don't think my ability to choose what I do "tomorrow at noon" is about my being able to "change" what happens "tomorrow at noon". There's only one fact about what happens "tomorrow at noon"; whether it's my choice or not is a matter of whether that fact is a result of what I do, not a matter of whether there are "two things" tomorrow at noon or whether I can change what happens "tommorrow at noon" from one thing to another thing
Given there's only one fact about tomorrow at noon (say, it's either true I'll do X, or it's true I'll do Y), there's nothing in principle forbidding an omniscient being from knowing what that fact is.
