The manifesto will be memory-holed. The powers that be will never allow anything so potentially disruptive to the LGBT narrative.
Judicial Watch or another similar organization will probably request a copy of it pursuant to that state’s public records law.
Do you think such a request can legally be denied? The shooter is known (no compromise of investigation, at least in terms of the immediate perp), and already dead (no privacy concerns).
And yes, they WOULD do such a thing as rewrite the whole thing. The DOJ is totally lawless these days....