Something similar happened in the Haskell community, where some people called for Anduril job postings to be removed.
Nix is a software project, not a social movement. The goals of Nix are entirely separate from how the software is used.
I really like Coinbase's statement that is is mission focused (https://www.coinbase.com/en-ca/blog/coinbase-is-a-mission-fo...). Anything that isn't directly related to its mission is out-of-scope. I wish the same was true about software projects like Nix.
If you care about the way your software is used, then by all means, say it in the license! Of course, such software won't get used much.
everyone loves to assert that Nix is this or that. whatever label you fight to place it under, it's a product of some thousands of people. whatever it actually is, it's underpinned by something social.
I think it's appropriate to separate concerns and use categorizations to help us separate ideological goals from practical reality. Paper is also used to fight wars, as are a myriad of other goods and services that exist in a more or less neutral space.
There's an important and very large conversation to be had about what we do and don't think is acceptable use of technology and general goods/services, but issues like the Nix meltdown seem like misapplied frustration at how resources are allocated (to buying things used for war) and an attempt to solve that allocation problem by cutting off supply instead of addressing the allocation of funds at the root.
Clearly some people think this is a good tactic, but I question both the effectiveness and the net good of such a tactic when the slope required to implement said tactic is indeed a slippery one.
I would prefer that code I write is never used for purposes I believe to be harmful. But this is fundamentally incompatible with the OSS model.