I'm just starting to read up on the bishop, but it's my understanding that they never took any formal disciplinary action against him.
Not directly. They force retired him in 1981, however, so this was before the consecrations. Bishop de Castro Mayer relied upon the notion that V2 was a "pastoral" Council and held that in his diocese pastoral considerations weighed against it.
By the time of the 1988 consecrations, he had become a sedevacantist.
I do wonder why neither Montini nor Wojtyla moved to remove him. I think that until Bergoglio started removing +Strickland, it was considered contrary to the principles of "collegiality".