That means that the potential attack surfaces are many. It doesn’t make the decision right for any other project. To be quite honest, I have these exact same concerns regarding the Rust rewrites elsewhere; but (for example) a Rust-based sudo would require that someone first gain shell access as a non-privileged user, and THEN be able to wield an exploit embedded in sudo. With something that is key to many web sites and other internet-connected services, the attack potential is far more direct.
And that would be a strong protection, if the only type of attack were one that hits everything all at once. Unfortunately, as Ken Thompson’s hack proved, this sort of attack can be extremely narrowly targeted. And Python is a juicy target.