and I have heard it said in effect - that to go deep into the bible is to cease to be a RCC and become a Protestant.
I've heard it said also, but I haven't seen it work that way very often. There are some pretty solid Bible scholars who are Catholics. Some of them used to be Protestants, too.
You wrote: "and I have heard it said in effect - that to go deep into the bible is to cease to be a RCC and become a Protestant."
But what you heard was nonsensical. The Bible relates historical events of Christ's life and the early Church. That's why so many Protestant ministers, who knew the Bible well as one would expect a minister to, became Catholics in recent years after studying the Bible more intensively: Scott Hahn, Gerry Matatics, Steve Wood, Robert Sungenis, Noah Lett, Jim Cope, and several hundred others.