I say the Church just wants to go ahead of the game.
They anticipated that the disclosure by science that Aliens do exist is imminent. Church leaders know that the evidences for extraterrestrial life is hard to debunk. Hardcore modern day scientists attest that alien life is completely rational when taking into account the vastness of the universe. Even high-ranking U.S. military officials could no longer hide the undeniable fact that aliens have visited the earth since the dawn of the early civilizations. (Remember the Roswell crash in 1947?)
World leaders also hinted to the nearing of a worldwide information disclosure about extraterrestrial life. What do you think would happen if UFO's and aliens had suddenly been proven to be true? Won't the Church have some heavy explaining to do? Won't the Church crumple to pieces if it can't provide possible explanations?
To avoid confusing its followers, the Church went ahead and proclaimed that Alien life is compatible with its doctrines! Silly Vatican. Here goes my own Catholic Church saying NOW that there may be aliens out there, when it ONCE ordered the killing of people who had believed in alien life 500 years ago. Poor people who were burned at the sakes and fed to the lions.
