Because the threat of mentions on one's permanent record sure stopped many would-be juvenile in grade school.
I get the distinct impression this rebuke is done for show because he went public, not because he opposed Catholic doctrine.
As Catholic in Brooklyn writes:
Father DeVito's cousin is in danger of eternity in hell fire. A Catholic priest should in no way lend his presence to such an abomination. A rebuke that is a permanent part of the record? No, I don't think so. Father DeVito knew this was wrong. He should not have been thereMaybe pro-lifers are a bit optimistic in expecting bishops to discipline wayward Catholic politicians if this is how priests are disciplined for their lack of orthodoxy.
H/T: The Deacon's Bench