I have no chips in the game, but the author does state:
> I’ve been using C since about 1993, and C++ since 2002..
> ..I later put a lot of energy into talking other teams at X into using C++, rather than straight C, for their firmware.
So a charitable reading of the flawed phrase "C/C++" would be C and C++, and the author clearly knows both well to back up his assertions.
All in all, I found the title a fair statement to make, he does offer plenty of reasons and even alternatives.
Your critique hinges on my being unable or unwilling to rewrite "prefer Rust to C/C++ for new code" as "prefer Rust to C for new code and prefer Rust to C++ for new code", then verifying that OP's argument applies to the rewrite.
The characteristics, best practices in, and pitfalls of C are fundamentally different than for C++. Anything that pretends to offer useful advice, but equates them, is certain to be deeply flawed. As, indeed, is TFA.