It’s not uncommon for viral DNA and mRNA to get into cellular genetics, depending on source and destination. Out genome is full of bits and pieces of invading genetics. That may be part of the issue. Kind of like when the Epstein-Barr virus genome ends up in our lymphatics genome and for some it leads to Hoskins lymphoma.
From an article- “ Clonal viral genomes can be found in the HL tumor cells, the Hodgkin Reed-Sternberg cells (HRS). The latent infection results in expression of the viral oncogenes LMP1 and LMP2A which contribute to generate the particular phenotype of the HRS cells. EBV does not only undergo epigenetic changes of its genome during latency, but also induces epigenetic changes in the host genome.”
Hence the entire mRNA can’t enter cellular DNA was just a flat out lie. It may not or it may. You have to test over periods of time and over a large sample to know that answer. The NIH/CDC/FDA gave a very misleading answer that was not based on the science of testing.
“Unlike genetic changes, epigenetic changes are reversible and do not change your DNA sequence, but they can change how your body reads a DNA sequence.”