Indeed. But Rudy has held up his father as a hard-working Brooklyn tavern owner, a “complete man” who taught him the “lesson of being honest.” If Rudy brags about the lessons he learned from his father then finding out his father was a felon and a leg-breaker for a loanshark, well that is relevant. At least imho. YMMV.
I do agree that if Rudy has clearly and knowingly lied about his father’s past, then that is in play.