So it appears from the comments here, that this teaching of St. Gregory of Nyssa was not misquoted, but that it was quoted accurately and that it presented a serious problem to the Orthodox theologians at the Council of Florence.
Well, if we are going to rehabilitate any of the erroneous teachings of the holy Fathers, then I vote for Saint Gregory's teaching of apokatastasis - that ALL of mankind will be saved and not one of us will be left in hell.
However, here is how the Church looks on such wrong teachings...
St. Photius the Great has expressed the Church's general interpretation in one phrase: "that in works of St. Gregory, Bishop of Nyssa, where restoration is mentioned, it is not accepted by the Church.
St. Varsanofios the Great, criticizing the doctrine of apocatastasis, when asked about St. Gregory's opinion, has answered: "do not think that people, though also saints, could completely understand all depths of God... Even if a saint speaks about such opinions, you will not find that he confirmed the words as though had the statement from above, but that they resulted from the doctrine of his former teachers, and he, trusting their knowledge of them, did not inquire of God whether it was true."
St. Herman of Constantinople has also expressed a negative opinion of the doctrine, but he supposes that the works of St. Gregory have been damaged by Origenists: "those who liked that absurd idea, as if for demons and for people who will be subjected to eternal punishment, is possible to expect the discontinuance... they have taken his clean and sensible works and have added the dark and disastrous poison of Origen's nonsense."
St. Mark of Ephesus, after citing St. Gregory, exclaims: "Are we wrong when we do not believe those words of St. Gregory of Nyssa, considering them forgeries, or, even if they are original, to not accept as contradictory to Scripture and to the general dogma?"
St. Maximus the Confessor, rejecting an Origenistic interpretation of apocatastasis, considered that St. Gregory used this term "in sense of restoration of cognitive forces of the man in that condition of the correct relation to truth." http://orthodoxwiki.org/Apocatastasis