You don’t buy the argument of the article that says the FBI memo is based on a hoax?
The FBI may perpetrate hoaxes, engineer them etc.
The FBI is extremely rarely to never taken in by a hoax.
There’s too much other confirmation around.
And in that era, J Edgar Hoover was eagerly trying to carve out some turf on that issue . . . in his usually demanding, powerful way.
Just my take on such things.
Certainly the FBI is as much into plausible deniability as other leaders are.
And they are certainly capable of muddying the waters in incremental efforts to out such information.