If you asked a random jews from 15th century Frankfurt about the fact that Jerusalem is mostly muslim (or a 6th century jew that it's mostly christian), what would his reply be?
Can you explain why you'd expect this to require justification?
They might justify it that they were waiting for the rebuilding of the temple. There was a lot of prophesy about the Jews being restored post Roman subjugation/diaspora. Also, I would assume that many Jewish groups would not feel that they had any obligation to live there. Even prior to the diaspora, there were very large populations of Jews living well outside the Holy Land, like in central Africa. Just because someplace is your ancestral homeland, doesn't mean you have to live there.