And they state that "it was possible on the following day."
But there was no poster session on the following day...

Of course he also disappeared from the online program. He was originally scheduled on Poster session 5, TV6 which worked fine on session 4 and 6.
(note: I wasn't there myself)

UNESCO’s response makes no sense at all and does not fit what I was told about what happened on site.

How a screen being turned off can be reported as :
"no space had been available to accommodate Ayup’s scientific poster”