It sounds like you are talking Arminian simple foreknowledge.
When Jesus chose Judas, he was not a devil or betrayer. Jesus considered him an apostle/disciple. Early in his ministy, Jesus would not have said these words.
He did say these words early in His ministry.
John 6:70 Then Jesus replied, "Have I not chosen you, the Twelve? Yet one of you is a devil!" 71(He meant Judas, the son of Simon Iscariot, who, though one of the Twelve, was later to betray him.)
Before Judas had agreed to betray Christ.....
Matthew 26:14 Then one of the Twelve—the one called Judas Iscariot—went to the chief priests 15and asked, "What are you willing to give me if I hand him over to you?" So they counted out for him thirty silver coins. 16From then on Judas watched for an opportunity to hand him over.
The o.v. asserts Judas was able to change his mind at any time and I agree. This being true means that Christ's stated prophecy fulfillment must have been foreknown.
John 17:12 While I was with them, I protected them and kept them safe by that name you gave me. None has been lost except the one doomed to destruction so that Scripture would be fulfilled.
He said them when Judas changed and it became a possible object of present knowledge to say these words truthfully. This is not foreknowledge, but present knowledge (which OT affirms, obviously).
Yet that present knowledge would have to yield exhaustive definite foreknowledge of Judas' future evil acts for the words to be true.
John Sanders develops the idea of Scripture illustrating/'fulfilling' a verse rather than it being a predictive prophecy based on simple foreknowledge of Judas. I am satisfied with his research and various examples.
It's a satisfactory explanation until we consider evil acts and God's inability to partake or participate with them. Then again we have Christ's words which are not 'illustrative' in nature.....
John 17:1 After Jesus said this, he looked toward heaven and prayed: "Father, the time has come. Glorify your Son, that your Son may glorify you. 2For you granted him authority over all people that he might give eternal life to all those you have given him. 3Now this is eternal life: that they may know you, the only true God, and Jesus Christ, whom you have sent.
4I have brought you glory on earth by completing the work you gave me to do.
5And now, Father, glorify me in your presence with the glory I had with you before the world began. 6"I have revealed you to those whom you gave me out of the world. They were yours; you gave them to me and they have obeyed your word. 7Now they know that everything you have given me comes from you. 8For I gave them the words you gave me and they accepted them. They knew with certainty that I came from you, and they believed that you sent me. 9I pray for them. I am not praying for the world, but for those you have given me, for they are yours. 10All I have is yours, and all you have is mine. And glory has come to me through them. 11I will remain in the world no longer, but they are still in the world, and I am coming to you. Holy Father, protect them by the power of your name—the name you gave me—so that they may be one as we are one. 12While I was with them, I protected them and kept them safe by that name you gave me. None has been lost except the one doomed to destruction so that Scripture would be fulfilled..
The prayer signifies specific foreknown action. Christ says that He revealed the Father to those who were given Him. Those included Judas Iscariot. That Jesus kept them safe and protected them. That none were lost except the one which Christ was unable to save as revealed through prophetic scriptures.
Are we to believe that Christ didn't protect and keep safe all those entrusted to Him including His enemy, Judas Iscariot? That Judas acts were not free in nature?
Simple foreknowledge offers no providential advantage to God (gets nonsensical when you start thinking about it). Even though you do not see it, I am convinced that EDF of future free will contingencies is not possible (emphasis on exhaustive and definite).
Then your statement isn't valid. It must yield EDF to be true. Christ couldn't say it truthfully until Judas fetched the soldiers. He said it long before this. Open theism must assert that it was unknown until it happened.
He said them when Judas changed and it became a possible object of present knowledge to say these words truthfully. This is not foreknowledge, but present knowledge (which OT affirms, obviously).
Muz's explanation that God waited until the Roman's were in existence fails because there was no way of knowing the Roman empire, which was a product of free will agents, would ever come into existence. Since free acts are unknowable according to the open view there was also no way of knowing that the Roman soldier wouldn't break with protocol and break Christ's legs. There was also no way of knowing that a bone wouldn't be broken during Christ's beating before the cross. There was no way of knowing that a free will agent wouldn't fall down in front of the cross carrying Christ and trip Him resulting in a broken bone. I could go on, but what's the point. Without foreknowledge of events there is no guarantee whatsoever of prophecy fulfillment.