In the past, authorities have authorized censorship on the basis of claims of substantial chances of social disruption or collapse if people were free to hear about religious heresy, alternate ideologies, sexually permissive art, losses in ongoing wars, looming disasters, and pandemic details. Quite often, those who pushed for such censorship benefited from it in ways well beyond the prevention of social collapse.
Some say that the US govt has long known of strong evidence that some UFOs/UAPs are aliens, but has shied away from disclosing this to the public out of fears that it might induce big social disruptions, such as riots or market crashes. Others call this a sensible fear, and call for careful study and elaborate plans before disclosure.
This all just seems quite wrong to me. First, people are mostly calm and orderly, even in huge disasters like the sinking of the Titanic. They may riot to express their anger, but not due to learning of some new scientific result. Relativity and quantum mechanics induced quite radical changes to our concepts, but led to no riots I know of.
Second, most of us are focused on the details of our lives, and not much moved unless the larger world makes a big effort to call something out there to our attention. And learning that some UFOs are aliens just doesn’t seem to imply much different for most lives. It is only a tiny fraction of us for whom our related abstract opinions might matter enough to us to make this revelation deeply disturbing.
Third, if in fact aliens have been visiting Earth for many decades, or even centuries, then they pretty clearly have long had the option to destroy us, intervene in our world, or clearly reveal themselves, options that they just have not much taken. They have also not been building or changing much near Earth, at least that we can see. Aliens aren’t trading much with humans, and any alien tech that humans have come across has clearly not given those humans much of a tech advantage.
So unless aliens plans are in some strange way sharply conditional on human elites coming to openly admit their existence, I see little reason why learning that some UFOs are aliens should change much. Aliens would mostly just continue to ignore us, and reveal too little to be of much use. Just as in prior decades. (A poll agrees.)
There might be much bigger consequences for human elites who previously ridiculed the idea of UFOs as aliens, and for human governments shown to have lied about UFOs. Those parties do indeed have selfish reasons to prevent disclosure.
I am highly skeptical of the idea that we are in the presence of space aliens. I am even more skeptical of the idea that we are in the presence of space aliens that are ignoring us. If they are here, then I assume their behavior is constrained by some version of Starfleet's General Order 1, the Non-Interference Directive, aka the Prime Directive.
However, I agree that UAP discloser won't crash society.
Live long and prosper.
I don't think it's possible to keep such a "juicy" fact secret if hundreds (at least) of officials (probably in multiple countries) have known about it for decades.
Sure we can keep the target coordinates of ICBMs secret, but those are *boring* details. We know ICBMs exist and the general sorts of things they're targeted at.
Every ex-President is asked about it and every one has said "not that I heard about", and then stuck to that to their grave. I think at least some would have said something else if the USG knew something.
That doesn't mean Little Green Men aren't around of course (tho I'm doubtful there too). It just means the USG probably isn't hiding them.