HAAA!
:)
Personal pet theory on why the FISA is being withheld:
Maybe the FISA-related everything ultimately points to the fact that a FISA warrant is NOT actually necessary anymore, due to the ongoing weakening of processes and systems that are supposed to protect the basic rights of Americans. Like the right to not being surveilled in your own home and without your knowledge, for example.
I think that "We have it all" applies to all of us. Normies, nerds, cabal, grandparents, perverts, and so on.
Soooo, why would anyone need an actual FISA warrant?
Also, I think it may turn up that there were some Russian mob-types running a gambling joint or something in Trump Tower and they were being surveilled. During the course of THAT the "coincidental collection" of info on the Trump folks was not handled in the manner it should have been, then was used to expand the surveillance to Trump and associates.
Ultimately, these are just thoughts.