One thing is fantastically hard to ignore. The SARS2 phylogeny is rooted by a most recent common ancestor in October or November. This is as clear as day and no evidence has ever surfaced to nudge the estimate nor to indicate the virus was present previous to those dates, nor that there were existing proto-SARS2 strains. These would continue to circulate and something would have been found had they existed. (n.b. There _has_ been some now discredited science arguing it was in Europe before those dates.) The correspondence between the virus phylogeny, this report, as well as previous indications of a shutdown in the WIV in early to mid October 2019, is just an awful lot to say maybe to. So, what's the explanation on the other side of your "maybe"?
You're asking me to comment on the entire theory, I think. I'm only commenting on the value of an unseen intelligence report of unknown source. None of what you've said increases the validity of this report.
Everyone commenting on this post is acting immediately as if this report is 100% true, but the reality is that we know very little about the report.
