Viruses don't "survive". If the virion isn't damaged, it must be able to 1) infect a cell 2) successfully replicate in the cell. Clearly, the bodies involved here are capable of providing a protected environment for virions to remain undamaged. Samples kept in a lab are often placed into cryogenic storage to prevent degradation. There is no host there.
“Clearly, the bodies involved here are capable of providing a protected environment for virions to remain undamaged.”
That’s not very good logic. You ignore the very real possibility that those 28 positive tests on a corpse for 6 weeks after death were just false positives, which is the more likely possibility. If viruses were able to survive in dead bodies, we probably would have noticed this fact at some point in the 130 years since their discovery.