Baptism is a sacrament cannot be “undone”.
It’s not just a catholic thing - a person cannot be “unbaptized” yes.
The catholic church recognized many baptisms outside of the church.
That Mel was baptized catholic prior to vatican II - does not make him a catholic now, just like any catholic who leaves the church for whatever reason.
Listen guys, my opinion is explaining the truth to Democratic liberals is like trying to describe a typewriter to a monkey. Why bother!