It is very silly to say that something is bad because it started a long time ago. I do not see how any of the modern languages of the 21th century would be even remotely suitable to write an OS kernel with. Considering that most of those languages are at least partially interpreted and require GCs, a kernel written in them would be painfully slow.

Just because something is old does not mean it is worse, and just because something is new it does not mean it is better.

If you think about it, the modern languages are clearly made for programming higher on the stack (i.e., at application level). That makes a lot of sense. After all most programming is done at the application level, and it would make sense to write a language that makes that type of programming easier. And of course many modern languages are very successful in that respect. But it is silly to assume that just because they are successful at the application level they would make good kernel programming languages.

The reason why C++ is the language being considered is that it is also a relatively low level language which means that it can potentially replace C for kernel level programming. That of course does not mean that it should, and Linus does a good job of pointing out the issues with C++.