A common response in the recent LessWrong threads about UFO's is rationalists immediately going into a state of wanting to translate the news into probabilities of the existence of aliens instead of taking the facts for what they are and thinking about what should happen based on the revealed facts.
According to Ross Coulthart, David Grusch gave the ICIG, Congress and the Senate, the location where the vehicles are stored and the names of the people who control access to those programs.
While I would like to know whether or not aliens visited earth, I think it's more useful to simply take the stance "I don't know" instead of thinking in terms of probability.
From the "I don't know"-stance, the next step is obvious: There need to be congressional hearings where the people who were named has being in control of access to those programs get asked in public about the nature of those programs.
Given that there seem to be powerful people in the intelligence community who want to block public exposure of whatever the nature of those programs are, it's important that there's public pressure on Congress to investigate and hold public hearings that go into the details.
The mental moves of directly rounding down to "my priors against aliens are high" -> "no aliens" -> "no need to do anything" is bad as if enough people hold it we won't get more evidence.
It doesn't really matter, any motivations from "someone wants to cause chaos" to "someone is literally crazy" to "the CIA is playing an elaborate distraction game as part of some other plan" are by definition more plausible than something like alien crafts traversing interstellar space unobserved and coming to spy on us and nothing else. Anything that only involves humans and doesn't require new undiscovered laws of physics to be realistic wins the Bayes lottery by orders of magnitude.