The molecular signature between ME/CFS and long COVID can’t be compared easily as majority of the ME/CFS patients accumulate secondary biological features over time. It seems that how the body adopts to the stress of the disease over time makes it different.
I assume he means 'adapts'?
It would be very surprising if there were no changes over time. Not just molecular, of course, but across all relevant health domains.
With at least some of those changes being necessary adaptations in order to survive such a major chronic adverse change in health and general life status. The rest being largely unavoidable adverse consequences, only mitigable to varying degrees.