The report says nothing at all about a briefing from a whistleblower.
Also, you can find accounts of UFOs in literature from the past 2500 years.
However, not too many people are brilliant enought to ferret out what is behind all the secretive stuff going on in the world that seems so easy for you.
I don’t claim to understand the details of what is behind all of it.
I can just use logic to observe the outline of it.
It was easy enough for the powers-that-be to silence Snowden/Assange/Yeakey/Webb/Rich. Why in world do you think they wouldn’t do the same thing to a UFO whistle blowers?