What the bishops are doing is called doubletalk:   they say they are against illegal immigration -- and then recite biblical justifications for why illegal immigration is justified in the eyes of God, should not be a crime, why it's necessary for the good of both the immigrant and the U.S. etc.

It's the oldest rhetorical trick in the book.

Likewise, when asked if they support "amnesty," the bishops say they don't like that word.   Then they give another long explanation of why amnesty is a good thing.   
https://www.flaccb.org/documents/2015/8/CatholicChuchonImmigration10-07.pdf

Whatever the general public's support for amnesty, it doesn't let the bishops off the hook for encouraging illegal immigration.