Consider Constantine, he was a grotesque tyrant, put off being baptized until he was on his deathbed, now he's a saint.
Just because the Catholic church calls someone a saint, doesn't necessarily make them one. On the other hand, just because you call someone a grotesque tyrant, doesn't necessarily make him one either.
God decides whether he was a saint or not. Water, Baptism doesn't save you. And deathbed baptisms were apparently common in the 4th century.