I'm glad this long-overlooked idea is finally being remembered. It does lead to two further conclusions of course: how can these frozen collapsing stars have spin? And how can they have magnetic fields or (detectable) electric charge?
It doesn't seem they could have either, so all the physics done on rotating and/or charged/magnetic black holes with real singularities seems to be making the rather large assumption that there are any that were formed at the birth of the universe. They can't form now so quite possibly don't exist. It has been shown that relativistic jets, for example, can be generated by the magnetic field of the accretion disc without requiring a spinning black hole.