I know this to be untrue, as I was at the seminary when various NO priests arrived to receive conditional ordination simply by their request. There was no investigation. One priest said he had no doubts about his orders but said he wanted to get conditionally ordained to put the faithful at his chapel at ease (since many of them did have doubts). No investigation was done for those cases about which I have first-hand knowledge from my time at STAS.
Okay, how does that change the subject at hand? It has never been the policy of the SSPX to automatically re-ordain Novus Ordo priests.
It really is futile to try to talk sense to sedevacantists. I give up. The SSPX will, however, likely outlast any of the sedevacantist groups. The SSPX has many faults, but extremism isn't one of them. That's why they are likely to survive (provided they don't reconcile with Rome).
And the Resistance is likely to split after +W goes to his eternal reward, so I place no hope in them at all anymore.