Your argument is completely specious. Re-read that list. Assembly is a second language in the kernel already, and really it's multiple languages, one per supported ISA. Perl and Python scripts are used to generate data tables; there are multiple build-time languages. eBPF is evaluated at runtime; the kernel contains bytecode loaders, JIT compilers, and capability management for it. The kernel has already paid the initial cost of setting up a chimeric build process which evaluates many different languages at many different stages.

Perhaps not, but if you’re a kernel developer, I believe you are obliged to understand your build system and tooling. The fact of the languages aren’t all used at runtime seems immaterial.

That said, I am no kernel developer, so take it with a grain of salt.