I am impartial on the matter, but I think one of the reasons Bun became a thing in the first place was because of Zig attracted a small but very active developer community. Switching from Zig to Rust effectively alienates that community.
If this were true the very small but active community of Zig contributors could just fork it and you could all return to the happy times of not using Bun anyway.
Bun became a thing because it provided some specific benefit to js ecosystem. Zig enabled the rapid development. The people who contributed were definitely helpful but they can still choose to help or not and new people will step up too
I think the Zig people are really just worried that maybe Zig itself is a DOA language before it has even reached 1.0 because it doesn't offer enough over C for any serious use and their flagship project has now abandoned it.