So, let us run a thought experiment. Pretend Isaiah 40-48 means what Calvinists claim it means: that God has exhaustive knowledge of the future.
Does that mean God has always had exhaustive knowledge of the future? When compared to Genesis 6, wouldn’t the more rational position (assuming Isaiah 40-48 means God knows the future) be that God acquired at some point between Genesis 6 and Isaiah 40-48 the ability to know the future?
God is Open 
No because God is the same yesterday, today, and forever. He can’t learn anything, there is nothing for him to learn.
Heb 13:8 Jesus Christ is the same yesterday, today, and forever.
Is this referring to Jesus?
Did Jesus ever not know something?
Mar 13:32 “But of that day and hour no one knows, not even the angels in heaven, nor the Son, but only the Father.
I dont think that verse means what you want it to mean.
You seem to approach texts with loaded assumptions that are not Biblical. The posting in question is asking a reading comprehension question, not a systematic theology question.