It is this very uncertainty that caused UFO information to be hidden from the public in the first place. They learned early on that most people wouldn’t be able cope.
With respect, 1) who is "they", and 2) how would "they" have learned anything?
Test marketing? Conspiracy theories? Movies? "Them!" from 1954. "They Came from Beyond Space" from 1967. How about "It" from 2017? Mars Attacks?
What exactly is it that "people" as opposed to the "they" (who apparently are coping quite well), will not not cope with, if all is revealed?
Some of the public has confronted the Mengele experiments from WWII? Or Ishii's Unit 731 from the same period? Or the Khmer Rouge's delightful depopulation decades back? How about the WEF's Harari's "useless class" notions (by which he probably means you and me)? I am truly unable to contemplate any thing that need be hidden because "most people wouldn't be able cope."
Could you offer an inkling of more of what you mean?