Working together is a two-way process. To land a big change, the bun people probably needed to have been working/coordinating with the zig people throughout. E.g., zig outright cannot accept PRs that break the language in unplanned ways and any conflicts with the roadmap would need to be resolved.
I would assume the bun people know all this. That makes it more of a publicity stunt than a serious attempt to contribute to zig, and we should probably all treat it that way.
I’m not sure how well the Zig developers have handled their communication, so perhaps there really was room for improvement there.