This would require using unsafe code.
> As in: literally heartbroken. Unable to talk about it.
I would hope that this person improves as an engineer, because this isn't particularly professional behavior, from the way you describe it.
> "But the compiler said it was okay!"
Given that you'd have to use unsafe to do this, the compiler can't say it was okay. It sounds like this person may not fully understand Rust either.
> it seems that Rust users seem to self-identify with the absolute infallibility of anything relate to the language, and react quite violently and self-destructively to any evidence to the contrary.
I don't see how this generalizes. You had one (apparently junior, given "mentee"?) person make a mistake and respond poorly to feedback. You also barged into this thread and made incorrect statements about Rust, and were downvoted for it. That doesn't mean that Rust users think everything is perfect.
> As a community leader, do you see any room for improvement there?
I do think sometimes enthusiastic people who don't understand things misrepresent the thing they're enthusiastic about, but that's a human problem, not a Rust problem. I do not think there's a way to fix that, no.