If you believe that Judas wasn’t Saved at some point, the implication would be that Jesus chose Judas in order for him to fail which would make Jesus appear to be duplicitous.
That’s not a good look for the Savior.
If you argument is that the proof that Judas was unSaved was the betrayal, that would be a self-fulfilling prophecy.
But Jesus didn't act or not act for appearance sake.
No matter what anyone does, SOMEONE is always going to find fault.
Here we had Jesus, perfect in every way, the the Pharisees still found fault with Him.
If being perfect wasn't good enough for them, then NOTHING Jesus could do would satisfy them.
Jesus picked Judas for the reason of fulfilling prophecy and being God, He had the right to do it, no matter how or if someone misinterpreted it.
There's a world of difference between appearing to be duplicitous and actually being duplicitous.
And often that is based on worldview of the person observing.
You’ve managed to ignore other possibilities. JESUS IS God with us. He has every sovereign right to select a devil, unsaved, never saved, to be in the company. Try not to limit GOD.
“I create evil.” Isaiah
“The Lord hath made all things for himself: yea, even the wicked one for the day of evil.” Proverbs