I think there is something wrong with them because they are failing to see that the c++ syntax has an abysmal complexity which propagates the toolchain implementation.
This is the only reason you need to make this language a definitive nono.
They should be ashamed of themselves, and if they are not, well, they are toxic, and they are doing it at worldwide scale.
Modern C++ with move semantics is a lot more easy to reason about and memory safe than C99, IMO.
Since it's a greenfield project, they didn't have to worry about the nasty baggage of legacy C++ spaghetti that kills most projects.
Just because you prefer "simple" C99 doesn't mean they do :)