(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.