It's not just Linus. I use C++ daily for a variety of things, but I understand the hesitance to use it in real-world kernels and embedded code. For instance: The switches to disable features like exceptions are generally considered "not supported, use at own risk"; removing them is not an official part of the language. C++ templates are slow to compile and have many obvious shortcomings — but if you avoid them, you're back to using C macros. The C++ abstract machine puts a lot of weird complications in the way, adding new UB landmines on top of C.

This doesn't mean using C++ for kernels and such is impossible, but anyone with a conservative, risk-averse mindset (like Linus) isn't going to want to touch it.

Rust, on the other hand, was deliberately designed for such uses, starting from a fresh sheet of paper. Giving systems programmers everything they want without any hidden "gotchas" is its whole raison d'être.