Yes, Stubborn isn’t distinguishing between the various reasons for excommunication. If a woman gets an abortion, she’s excommunicated but if she’s still practicing the Faith, she’s still a member. If someone like Martin Luther is excommunicated for heresy AND THEN STOPS PRACTICING THE FAITH, he is obviously not a member anymore. Faith is required for membership, as multiple popes have said.
Excommunication is like a parent keeping an adult child at arms length from the rest of the family for fear the bad example will infect the others. It doesn't mean the child is not a family member. It means he's not welcome until he mends his ways.
A "vitando" excommunication means the person is never welcome back. Again, he's still a member.
A non-practicing Catholic is just that, non-practicing. It does not mean he is not a member. It means he is less likely to get to Heaven.
Baptism makes a person a Christian, a child of God, an heir of Heaven and places an indelible mark on his soul. A baptised person is a member of the Church and always will be.
Don't get lost in the thicket.