No one disagrees with that. If you aren't interested how that works then you need go no further.
We know how it works, it is not a mystery that you seem to think it is.
Did the soldier truly draw his bow on a chance shot according to his own free will or not? Yet, if that was the method God wanted to use to kill Ahab then did it have to happen as a necessary yet secondary cause. Calvinists say yes to both questions. The only difference is that the scenario, which is obviously what really happened, could not have for sure happened with your definition of free will because the man could have decided not to take the shot up until the time he actually took the shot. According to your system God cannot have it be true that the man must take the shot because that would violate your own definition of free will.
To say that God has exhaustive foreknowledge because he is God is fine if you also allow a Calvinist to say God determines everything yet allows man's free will - because he is God. Don't tear into someone else's statement when you can't defend your own.
The text says " Now a certain man drew his bow at random and struck the king of Israel in a joint of the armor." 1Ki 22:34 Do you not believe this? The question you have to answer is did God foreknow that the man would do such a thing. The answer is YES. Did God's foreknowledge cause that to happen the answer is NO.
The man could have not taken the shot but he made the free will choice to take the shot which is just what God's foreknowledge of the event would actually be. If he had chosen not to take the shot then that is what God's foreknowledge would have been. So God could know it to be true because of the foreknowledge that you do not seem to be able to grasp.
Free will is the capacity for agents to choose between different possible courses of action (aka choosing “otherwise”). This does not require the person to be able to choose anything, nor does it require the absence of other influencing factors. It only requires the ability for a person confronted with a decision to be able to choose from among one or more possible options.
To say God foreknows all that will happen and man has a free will is logical but to say God determines all things yet man has a free will is illogical, it is an argument that I have seen many times from calvinists but it does not hold any water.
If you want to say God determines everything than accept the logical end of that view, He is responsible for all the sin as He determined that it should happen.
You may not like what I have said regarding free will but you can not say it is not defended.
The bible gives clear evidence of man's free will so what better defense do you need?
We are told to choose Deuteronomy 30:19-20, Joshua 24:15
We can resist or even reject God’s grace Acts of the Apostles 7:51, Hebrews 3:15
Salvation requires an act of faith John 1:12, Romans 10:9-10
We can seek and find God Jeremiah 29:13, Acts of the Apostles 17:27