But isn't it essentially just taking away time as a factor which is pretty much what predicting via determinism would do?
Maybe the general definition of free will most people seem to go with just doesn't deal with weird edge cases because it basically developed to fit reality.
I'd argue that an all-knowing God is something that can't really be reasoned about. It's the introduction of an infinite value into the discussion (or maybe more like a division by zero?). You end up with logically contradictory statements when describing the properties of such a being.