Perhaps it is more appropriate to say that he didn't provide the evidence, not that he couldn't. Secondly, we don't know why unless you were a fly on the wall in the court room. I trust you get my point. And this without getting into the Koch's postulate definition.
Also, I think Sinister Burt reminds you below about our previous conversation regarding covid deaths.
It is also my reading that the 28 days UK definition seems unique and not applicable to other nations. Not that it matters since the excess deaths (in the UK) show an 'abnormal' spike which roughly correlates with the (UK's definition) covid deaths as reported.