Is it possible to hold 1) that Luther's views on justification are heretical, 2) that Pope Francis states that Luther's views on justification are correct, and yet not conclude 3) that Pope Francis himself is a heretic?
I take it that 1) is indisputable. All Catholics are bound to accept 1), on the basis of Trent but I think also the whole previous tradition. It would probably be applicable to what is condemned by Trent and not Luther's own words, but it is hard to argue that the two are unconnected. Look at Chemnitz or Luther himself. 2) is correct if we believe the recent transcript. I take it that 3) is possible but most probably incorrect.
It seems to me that 1) and 2) would entail 3) only if it were restated as "Pope Francis assents to Luther's views on justification," and it would entail formal heresy with contumacy only if it were restated as "Pope Francis assents to Luther's views on justification in defiance of earlier Church teaching." The Pope may have had in mind the joint declaration on justification. As Chris Malloy, Avery Dulles, and others have shown (which is not at all difficult), this declaration was theologically incompetent, and motivated more by false ecumenical ends than by historical or theological accuracy. If the Pope consequently doesn't understand the issues, it is arguable that he is not a heretic. Hence 1) and 2) can be true, and yet 3) false. There is a difference between being intellectually unable or perhaps unwilling to grasp certain basic issues and being a heretic.
For the transcript, see http://m.ncregister.com/daily-news/full-text-pope-francis-in-flight-press-conference-from-armenia/#.V3FsU00UXIV
"I think that the intentions of Martin Luther were not mistaken. He was a reformer. Perhaps some methods were not correct. But in that time, if we read the story of the Pastor, a German Lutheran who then converted when he saw reality — he became Catholic — in that time, the Church was not exactly a model to imitate. There was corruption in the Church, there was worldliness, attachment to money, to power...and this he protested. Then he was intelligent and took some steps forward justifying, and because he did this. And today Lutherans and Catholics, Protestants, all of us agree on the doctrine of justification. On this point, which is very important, he did not err."
I wonder if it is harder being a Catholic now than in Luther's time?