Are you familiar with Bishop Williamson? He is most definitely misguided, though perhaps well-intentioned. He’s even threatened schism within SSPX if Bishop Fellay pursues reunion with Rome.
And you answered your question with what could possibly be misguided about Traditional Roman Catholicism. The movement in and of itself is not misguided, but when it delves into Sedvecantism and Anti-Semitism (as it sometimes in certain groups does), it becomes misguided.