C++ is well-known and popular.
It's nearly a superset of C90, which GCC was then written in.
The C subset of C++ is as efficient as C.
C++ "supports cleaner code in several significant cases." It never requires "uglier" code.
C++ makes it harder to break interface boundaries, which leads to cleaner interfaces.
Again, I mostly agree with everything you wrote, but this is overstating things a little. Because exception safety can be a little more complicated than it first appears, you do end up having to do a bit more work in C++ in certain cases.
One example of this is writing an external ABI in C++. Depending on how nice you want to be to the consumer of your ABI, you might need to add a try...catch(...) to every public function to make sure exceptions don't escape the C++ code. There are also tricky subtleties around writing, say, a swap function in the face of constructors that might throw.
Also, in the article it states that cars are using C. If I'm not mistaken, Bjarne himself in a couple of videos he has mentioned certain companies, like BMW and Mercedes, are using C++ for their cars and of course these two companies are not the only ones.
The good thing is that C++ committee did pay attention to what people and companies have suggested and or complained for years and fixed it with the release of C++11.
I really love using C myself, but I wish C had the safety C++ has by default.
That's not "required" if you write the C++ code yourself though, as you can just refrain from using (throwing) exceptions in the first place.
That's what the parent means.
(1) So the gcc codebase is almost entirely C but it is compiled as C++. Someone else might be able to explain exactly what features of C++ made this an attractive option . My intuition tells me it has to do with better compiler diagnostics, perhaps involving type checking. I'm on mobile or I would research and provide more authoritative sources.