Zig is way easier to verify than rust code (no hidden control flow, no hidden allocations that might fail, ...) which means a security expert can read a single function (without knowing more about the code) and can reason about that function.
This does not work in languages like C++ and Rust where RAII is a common pattern and code will be implicitly be executed when some objects go out of scope.
Yes, sure. Rust does a lot of verification work already, but so do tools like cppcheck and other verification tools and i'm sure those will emerge for Zig as well.
Zig (in contrast to C or Rust) has no warnings. Behaviours that might not be OK are compile errors and cannot be ignored. There are also plans (as in "not implemented yet") to forbid declaring unused variables and such so even this gets a compile error. This makes Zig also easy to reason about (seeing a variable declaration means that it's guaranteed to be used later)