No. A.W. Tozer never commented on "The Openness of God" theology, or "Openness theology." This theology developed long after A.W. Tozer went to heaven. Openness theology claims that God is not omniscient in knowledge concerning the future, therefore the future contains several contingencies. While Tozer did not have any contact with openness theology, he certainly had a theological response to it, as well as the notion that God could not determine the future. Writing about God's infinitude, Tozer states:
If there were a point where God stopped, then God wouldn't be perfect. For instance, if God knew almost everything, but not quite everything, then God wouldn't be perfect in knowledge. His understanding wouldn't be infinite, as it says in Psalm 147:5.
Let us take all that can be known--past, present and future, spiritual, psychic and physical--everywhere throughout the universe. And let us say God knows all of it except one percent--He knows ninety-nine percent of all that can be known. I'd be embarrassed to go to Heaven and look into the face of a God that didn't know everything. He has to know it all, or I can't worship Him. I cant worship that which is not perfect.
What about power? If God had all the power there is except a little bit, and if somebody else had a little bit of power hoarded that God couldn't get to, then we couldn't worship God. We couldn't say this God is of infinite power because He wouldn't be of infinite power; He'd just be close to it. While He would be more powerful than any other being and perhaps even more powerful than all the beings of the universe lumped together, He still would have a defect, and therefore He couldn't be God. Our God is perfect--perfect in knowledge and power.
Attributes of God, vol. 1.