The whole point of the outrage was that 1.4 was merged into main. Publicly. So I’m not sure what you mean.
Everything is in the open: PR #30412
That PR is the rust rewrite. That's some time in the past now. As of this comment, there is no tagged 1.4 release. This is the present. Anthropic is using apparently a version of Bun that is not publicly available. This is orthogonal to it being Rust-based, as all Bun releases now will be.
> The whole point of the outrage
Ok, go ask those people what they think then, I feel no outrage over a project switching language or merging whatever. But when once-semi-transparent projects become more opaque after an acquisition, I'm starting to readjust anything to the project I had in mind.