In the case of this article, even assembly isn't low level. It's not possible at all to write low level code for a modern superscalar CPU.

So no, Mojo wouldn't be low level. It can't be.

A bit of a nitpick, but from the article: "A low-level language for such processors would have native vector types of arbitrary lengths."

Mojo has exactly this with the SIMD struct: https://mojolang.org/nightly/docs/std/builtin/simd/SIMD/