I'd say the author, although they are right in most of their arguments, just want C to be a higher level language, well defined, well supported by every OSes out there in the same way.

I'd hate to see that happen, and I write C every day, read hundreds of lines of C everyday, and actually formally prove C everyday. C is not meant to be Rust or Go or Java. I'm actually against most of additions those days to the new standard. They complicate things, the (barely) portable assembly it's meant to be. I wouldn't write a database in C today, but I'd be happy to start a new bootloader project in C tomorrow.

The author is actually angry that the OSes still expose a C interface when they should use something higher level, like it seems Apple is doing (I may be wrong). I get that, but like we say in France, don't discard the baby with the bath water. The problem is that, as they say clearly, C is the lingua franca. C isn't the problem, its use is.