Uhm, no; it's because there's no comparison with Old Catholicism. Sedevacantists are merely applying a probable opinion regarding what happens to a heretical pope and have made a judgment that the V2 papal claimants have been heretics.
Applying a probable opinion, no. They usually believe with absolute certainty that the Pope isn't the Pope, or as in your case, that the pope has limited jurisdiction, and anyone who disagrees is a heretic.
The Old Catholics had an issue with jurisdiction. Do you not also have an issue with jurisdiction?