Is your problem with it that he decided to use Rust for that project or that he decided to move away from Rust for that project?
I'll give you an example of my impression of their comment. You ask your child to clean their room when you leave for work. When you come back, you find them having not cleaned it.
In retaliation, you say "I had spoken to the baker to make you your favourite cake for this weekend, now I'm going to call them and ask them to no longer make it".
The cake is "part of the public domain" of whatever thing they were working on, because if they were working on a private codebase nobody would care if they wrote it in D or E or G.
Read what you may of it. To deal with emotionally manipulative people in our lives, we've learnt to identify cues like this one. There's a reason why when angry the best advice is to bite one's tongue.
Honestly, the only emotionally manipulative thing I see here is you. You're trying to make something huge out of the simple statement of "this is making me not want to use Rust for the project I was gonna use Rust for". Someone choosing a different programming language is not a Big Deal.
This is so incredibly psychotic, you'd have to walk on eggshells and make sure to never publicly talk about your choice of technology stack to not upset you people. No, people are allowed to talk publicly about what language they pick for their projects, and they're allowed to publicly disclose when they reconsider. Anything else is literally insane.
I'm wondering what my parent comment thinks is so wrong about that (the "you can't really quit the way you did, and then dangle things like [0]" comment).
Anyway, he should pick language on technical qualities. That way he can avoid drama.
I don't understand why you believe you're in a position to say what anyone "should" use as criteria for picking a language. If a language's leadership and most prominent community members were mistreating me and lying about me for half a year I might want to avoid that language too.
I missed it was pointing to specific comment and not the link to article. And his previous statements on Rust gave me impression he's forever done with it. Mea culpa.