But copyright and plagiarism are orthogonal, and questions of morality are much more tied to the latter. It would be illegal (in the United States) for me to publish a copy of Nineteen Eighty-Four, but not immoral. It was not immoral, in my view, for Aaron Swartz to try to liberate JSTor articles.
That doesn't make plagiarism acceptable, either. And therefore, I'm willing to call it out when I see it.
Anyway, I don't see how this relates to the original discussion. Nor do I think the irony is particularly deep: As far as I'm aware, Deep Blue didn't plagiarize Kasparov, and indeed alpha-beta search is quite different than how humans calculate. But yes, I'd have been very demoralized if I were Kasparov, although he seems to be doing well now.
Edit: Regarding being mean-spirited, sorry to say, but I don't particularly care for the feelings of someone who has been repeatedly dishonest and used LLMs to respond to people engaging in good faith. That latter path has been exhausted now.
To co-opt your conflation of legality and morality: free speech, mf!