As far as I know -- Mathew can correct me if I'm wrong -- Tom stayed away from Mass attendance at the Institute in Rockford. Instead, he would go to Father Frank Slupski's independent chapel and continued going there even after Slupski was consecrated a bishop.
Yes, he didn't go to that chapel, although many of his employees did. He didn't fire them or excommunicate them for doing so.
But he was definitely a real Trad, if ever there was one.
He didn't foment needless divisions though, he's my model and hero in that regard. He sold pre-Vatican II Catholics books (like I sold Gregorian Chant) -- something even "conservative Novus Ordo" can use.
Why put up unnecessary barriers to your Catholic books?
Certain things: books, chant, rosaries, chapel veils, statues -- are "Trad-cuмenical" by nature. They don't get involved in the various controversies and disagreements in the Trad world. Least of all the Pope question.