I think it's a bit disingenuous to write that Linux uses C++. Clearly, the kernel is in C, and nothing else. There is no C++ runtime support in the kernel.

I get that there are userland applications in C++, but coreutils and all the GNU apps traditionally used in Linux distros are in C. And if you're counting userland apps, then you might as well say that Python and even JavaScript are the language of Linux, particularly since their use is growing more and more in most distros. Clearly, no one would make such a claim, so why for C++.