I would give at least embedded development a pass, since you rarely do have a choice there
Not because there's no other options (and long before Rust had its name coined)
Is it acceptable to risk buffer overruns on the HTTP server running on an insulin pump?
(maybe this will eventually be part of the UL/CE requirements, "contains no C code")
It's more even than having a single foundation oversee it. C and C++ are largely immune to, say, a foundation dissolving because one day it turns out its members cannot comport themselves as responsible adults and a big enough drama ensues. The fact that C and C++ have no singular "community" to speak of is a very strong side.
So when there are at least two (or better three) fully independent implementations of your C alternative, we'll talk about gatekeeping C.
Now, if you are a vendor and capital owner, nothing forbids you from forbidding C within your company and devices you produce. That has been your prerogative since forever, predicated on your ability to afford it. I'm more wound up about activists and evangelists trying to impose their hobby horse upon others. You do you. Show, don't tell.
At some point you just disallow horses to go onto the high-speed road, and aren't waiting for literally every last farmer to sell their horse over a car.
We should not be developing new projects in C, and we should make it politically hard to make new projects written in C in distribution repositories. C is going to stay around for a long time and that's okay, but there are so many inherent problems of its design and implementation that make it unsuited for unsupervised use. I wish that we didn't have to make such hard-line stances about this, but people have continuously proven that this tool is unsuitable for modern development and it's only going to get worse as time goes on.