The Council of Trent taught dogmatically that either baptism or the desire of it was required for salvation. (The Latin of the decree is aut voto eius. A Feeneyite gentleman of my acquaintance tried to tell me that aut voto eius meant "and the desire of it". That's false; any Latin dictionary proves it quickly.)
Who is Hilton?
Trent taught that either baptism or the desire of it was required for justification (not salvation as you wrote).There's a big difference.
The problem with baptism of desire, is that it splitting hairs, asking the question: What happens to a person who is pre-justified before receiving the water of baptism, and dies in that condition? St. Augustine called it the vortex of confusion, to think that God could give the grace for conversion of the hardened sinner, then could not keep the person alive long enough to have any passerby pour the water and say the few words.
Anyhow, baptism of desire does not apply here to this thread, since we are talking about baptized Catholics who have left the Church