I think most conservative Catholics are aware of this and disapprove of it.
This what is known as a prudential issue. The bishops have given their opinion, but it has no force, unlike the abortion issue. People can take it or leave it.
Frankly, the U.S. Council of Bishops is a loser, more often than not.
To be fair on the bishops, I believe they are supporting this position because they think it is the compassionate thing to do. I'm afraid they favor unlimited immigration, period.
The bishops are political dummies, for the most part. They should stick to what they understand. And, yes, I'm a Catholic.