Does the incompletely POC do all the parts, or doesn't it? That is no criticism against the project itself, striving to improve memory safety in any language is an honorable goal. The cinch is that an incomplete POC doesn't prove things one way or another, the POC needs to be completed (or at least completed far enough to prove your point). It either matches or exceeds Rust memory safety, or it only vastly improves Zig memory safety. Both are great outcomes, for what it's worth.
It shouldn't have been shown as an example of how Zig is just as/more safe than Rust if it is not. Mispresenting the project tears it down, not questioning its use an an example. Just like misrepresenting Zig's safety (and Rust's unsafety) tears Zig down.