Because God is able to view past present and future simultaneously, he knows beforehand how his work tuns out, and since he cannot be wrong, there is no free will. You have essentially listed all the properties of predestination here. God doesn't 'allow' anything because he was responsible for all conditions and thus, all outcomes; and he is aware, at the beginning, what they all are at the end, infallibly.
Essentially your entire set of paragraphs renders void your own sentence of " In terms of freewill, God allows man to choose his future." Given everything else you say, that sentence makes no sense.
I'm just saying such a being would have the potential to alter the past present and future at will. Not that they necessarily do.
So God could alter at any moment the past present and future to where is was as if man never existed. Or say altered the past to where Jesus didn't die on the cross. That could include altering our memories so to us if would be as if the past had always been so. We wouldn't know any difference.
So for whatever reason, God created a reality, gave man, an independence of thought, action and withholds from it his will. So while he could change anything according to his will he doesn't. So while knowing what will happen. It's already all happened as far as this being would be concerned. God allows it, from our perspective to run it's course. Basically not controlling man as a robot or puppet.
Like when writing a story the author dictates entirely the actions of the characters in the story. Whereas here God creates the circumstances of the story but gives the characters freewill to act independent of the author's will/desire for them to act. Being omniscient/omnipresent God knows the outcome but didn't dictate it.