Anybody not boggled over the idea of their program burning 21 MW for as long as it runs either can never be impressed with anything, or has no head for numbers. Computation demanding power that could hurl a fully loaded jumbo jet into the sky is not something most of us will ever code.
Many who have worked at AWS, Meta, Google, Apple, or Microsoft have had access to resources on that scale. That's hundreds of thousands of engineers by now, if not millions. You may be right that it's not most, but it's not rare either. And I personally think that running a supercluster for atmospheric modeling or whatever they intend to do with this thing is an ethically OK application of energy compared to hosting Cow Clicker or whatever.
Since it is at a nuke lab, one guesses that it will mainly be for nukes. Which, technically, could have some effect on climate processes if they were to, say, initiate an end to major CO2 emission (after the cities involved finish burning down; anyway burning steel does not produce CO2, a plus.)