god has no free will

[Heywood]

I view omniscience as knowing all that is knowable. Until God chooses to make the sky red or blue that knowledge does not exist.

So God is omniscient because he knows everything that he knows. I could use that logic and make a similar claim that I know everything that is knowable. If I don't know it, then that knowledge doesn't exist (for me). Even if you claim that there is someone else that does know it, I don't know that knowledge indeed exists. Maybe the sky was destined to be blue whether God wanted it to be or not, but God didn't know that until he chose that.

Negative JonDarby

The set of all that is knowable is not necessary the same as the set of knowing everything one knows. I know many things, but I do not know all that is knowable. You have made a straw man argument.