Ezekiel uses lions to symbolize powerful nations. Take his description of the princes of Israel:
He prowled among the lions; he became a young lion, and he learned to catch prey; he devoured people. And he ravaged their strongholds, and laid waste their towns; the land was appalled, and all in it, at the sound of his roaring. (19:6-7)
We're not sure, but this may in fact have a little-known connection to the Vampire Weekend song, "Young Lion" (though Rock Genius claims it's a reference to Jeremiah). At any rate, whether it does or doesn't have anything to do with Vampire Weekend, the "young lion" has a double-edge to its symbolism: yeah, lions are kingly beasts, but they can also be violent and savage like the oppressive and corrupt kings of Judah. So when this lion gets hauled off to Babylon, it's for Israel's protection.