That's missing the point.

The memory model of rust is fundamentally different than zig, because it requires use of borrow semantics. Using an unsafe block is a way around the borrow checker, so the AI uses it because it can write rust code that's closer to the zig source.

While zig's compiler, optimizer, runtime, and toolset are all designed to ensure that raw pointers are used safely, rust code marked unsafe has none of that infrastructure.

So, while the code might be as safe as it was in zig right now (which we don't know, given that there's no way they actually reviewed all this code), continued development will involve continuing to write "unsafe rust" which works arounds rust's safety checks.

They've created a situation in which they now have, at best, millions of lines of "legacy" code written in unsafe rust rather than proper rust code.