Well, "nuts" as a compact concept arguably is more efficient, as touched upon below (at the very bottom). But in other contexts...
"You know the Uphaven Hawks are going to beat the Podunk Buckets. It's nuts to think otherwise."
IOW, the ball game is decided by playing on the field (or court), not determining the outcome on paper by comparing the stats and injury lists of the two teams. Playing the game in reality (rather than simulating it) is what allows surprising upsets to be possible.
Another analogy would be how science research tests or investigates things rather than doing the philosopher approach of armchair evaluation, calculation, or contemplation. (Rationalist: "Oh, this is clearly nuts, because my reasoning arrives at that conclusion.")
At least the government is probing the validity of something "wild" for once. Instead of -- in comparison, cities that implement unvetted social policies that turn them into shoplifting toilet holes (among other things).
That said, however, I surely still occasionally shout and beat a shoe on the podium about something being "nuts" (actually perhaps many times about many things), but to no avail in terms of intimidating the applicable faction into submission.
"Nuts" needs to be unpackaged as something more substantial than dogma, or a pretentious proclamation of possessing omniscience, or appealing to a popular stigma/taboo, etc.
And even if there is weighty content to unpackage from "nuts", then the endeavor could still be futile.
This is why, despite the above, many of us do economically declare an _X_ to just be "nuts". It's quicker (saves two or threes weeks of elaboration and ineffective arguing) and is not much less impotent than that other lengthy route that usually also fails to dissuade individuals who are truly and deeply entrenched in a view.
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I think everyone understands what I mean by nuts and I've already in previous posts indicated why that is my view. But for the avoidance of doubt I can enumerate my reasons:
1) The likelihood of alien visitation is extremely low, given the rarity of environments for complex chemistry to arise, the enormous distances involved in space travel and the maximum speed it is possible for any object with mass to reach. So any alien civilisation would be most unlikely to send physical spacecraft to reach us. Their efforts would almost certainly be directly toward use of the EM radiation spectrum, which can at least travel at c, rather than anything involving physical objects.
2) The likelihood of any organisation keeping secret, supposedly for half a century or more, a programme involving contact with aliens, is very low. It would be at the cutting edge of science and would require the involvement of numerous experts in a variety of fields, spanning generations. It would leak. Furthermore it is hard to see why only one country's government would be singled out for contact. If there were alien contact, it would be apparent in more than one country. They would not all want to, or be able to, keep it secret.
3) There is no credible motive I have ever heard of for any government to want to keep such alien contact secret. What could conceivably be the point of doing that? Given it would be, as I say, at the cutting edge of our science and technology, it is far more likely that assistance from the international science community would be sought, in open fashion.
The low probabilities of (1) and (2) are of course multiplicative, lowering the likelihood even more.
Whereas:
4) There is a well-recognised psychology of conspiracy theories, notably in the USA, involving mistrust of "the government". Examples abound. The present time, given the rise of the internet and of Trumpy politics, is particularly fertile for such conspiracy theories, as we are all painfully aware ("deep state", "stolen election", vaccine paranoia, QAnon, and so forth.) It may not be going too far to say that the USA is undergoing a collective nervous breakdown at the moment, in which all kinds of wild, unevidenced ideas are taken seriously, by alarmingly large segments of the population.
It is in this climate of borderline madness that we now have this UAP investigation going on - in the course of which a Republican, i.e. Trumpy, senator now makes an allegation of a cover up.
That is why I label the notion of a cover up of alien contact as nuts. I hope that clarifies it sufficiently.