Rereading the Pope's homily, I didn't see that the Pope said the Last Supper was not a passover seder meal. He said that there is probability that Jesus celebrated the passover according to the Qumran community calendar, not the temple calendar.
Rather ... Temple cult than calendar. Got to remember no one Jewish sect held a majority over the others. Sadducee's and Essenes split over this, and other issues, the Maccabees revolt didn't fully succeed. Customs of the fathers or traditions of the elders, remember the Essenes insult to the Pharisees �Seekers of Smooth Things� comes into play. Then regarding, the book of Jubilees this is a early Pharisees work which is based on the Enochen calendar system of Qumran.
Pharisees at Jamnia purging of these early works, and other material pointing to Jesus as Messiah, what people consider Jewish calendar was a later work from the 4th century AD. Ancient Judaism practice in the first century was a diverse as Christianity of today.
