This is absolutely false, in fact the reverse is true! Public VOD on a public livestream is the default. It has to be switched off, either by deleting the streams, or making them 'private'.
What is also true is that, as long as a stream is under 8 hrs, YT has an "editor" which permits trimming and "save as new".
My guess is that this is some kind of legal red tape, speakers signed off for livestream but not VOD. If just one speaker objects, it can take the whole thing down.
I will mention, that in the case of Hosein Badran's presentation, I asked for, and received, permission to simulcast. It is available at
https://isoc.live/11782/
joly