I don't think you can separate out those issues. The pope is the Bishop of Rome. Therefore, if the NREC is invalid or at least doubtful, then the papacy of a man consecrated by it is logically called into question...which is why the SSPX changed its tune in 2005.
Many would make that very argument.
For myself, the whole matter is so complex and beyond my own comprehension and abilities, that any decision would be rash.
Consequently, I choose to presume the legitimacy of the current/recent Popes until the Church says otherwise, which seems the safest course.
"Fools rush in where angels fear to tread."
I would back away from my previous statement (i.e., That the validity or invalidity of the new Rite of Episcopal Consecration is not strictly a sedevacantist issue) before I would back away from this one.