Joseph: his comment never said anywhere that they didn’t find out until after they became fully frum. Why do you need so much for the world to believe this is a real problem?
BT’s find out their goyim in their “Baal Teshuva process.” They then either give up, or become gerim. Even if you find someone to come and tell me they knew someone who didn’t find out until he was “fully frum,” I would almost guarantee that person has a different threshold for “fully frum” than I (or you on every other thread in the CR).