What do you think they mean?
Want to explain where in UUS he embraces the "false opinion"? Actually he specifically condemns it in 11-13, and Card. Kasper references that part of UUS to show that Jesus' prayer for unity really did work.
Let's see what you've said previously on this subject:
Just as his false opinion that Christ's prayer was not fulfilled is prevalent throughout the encyclical.
What does JP II actually say?
Jesus himself, at the hour of his Passion, prayed "that they may all be one" (Jn 17:21). This unity, which the Lord has bestowed on his Church and in which he wishes to embrace all people, is not something added on, but stands at the very heart of Christ's mission. Nor is it some secondary attribute of the community of his disciples. Rather, it belongs to the very essence of this community. God wills the Church, because he wills unity, and unity is an expression of the whole depth of his agape. (UUS 9)
Where specifically does he say that? I'd have expected you to cut and paste that direct statement for everyone to see. Where is it? Why do the Protestants over at Ecumenical Review think it was directed at them?