Why not?
They aren’t following Catholic doctrine, are they, if they are doing something that the Catholic church does not teach?
If they are practicing non-Catholic doctrine, why aren’t they wrong?
They are following Catholic doctrine, and a bit more. An unnecessary bit, but it’s no big deal.
When I’ve heard the term ‘born again Catholic’ it wasn’t in reference to being born again in Christ. It was referring to someone returning to regular practice of the faith after a period of backsliding or faithlessness.