This is a valiant effort, but I am very pessimistic as long as Linux is written in C. I am also skeptical building Linux with LLVM will help much: it will help, but not much.
Vulnerabilities will always exist regardless of choice of language.
As soon as you port from C or C++ to Rust, much less vulnerabilities will exist. Much less than playing with LLVM build.
The devil in the details: “as soon as” here means more than a decade even for a very intensive rewrite of Linux in anything else.