You can do CHERI with Rust exactly as it stands (and people have done that), it's just that usize and isize are bigger than you'd want because now we're stashing provenance, so the other options are worth exploring.
Rust actually talks about provenance (messing with pointers is of course unsafe so it doesn't need to worry about this in most of The Book) so this isn't a mystery in Rust. Indeed the API as it stood before Aria's work already makes it clear that you're stepping off the edge of the cliff if you try to do address arithmetic and similar provenance defeating magic. Aria's "Tower of weakenings" is about firming up some of those first steps, allowing us to do some Road Runner don't-look-down bullshit and know whether we can get away with it on real hardware with the real compiler, while still forbidding things that are definitely crazy (the ISO documents say such things work in C++, but they do not work in actual C++ compilers, they have, drum roll... Undefined Behaviour).
Aria did a bit more than write some blog posts, for example:
Again though, this isn't about licenses. Regardless of why you don't have source code, that's where the problem is. "Gee, it's difficult to compile this program without source code" is maybe something where C wants to draw a line in the sand because of its very simple ABI but C++ is a long way past the point where that's useful and people need to stop pretending otherwise, it's a cause of enormous frustration in the community.
Ironically you point out CHERI, so when is the Rust memory model going to be fixed to fully support it, and catch up with C and C++ on that front?
Is Aria done with her blog posts?
The ISO clay tablets do happen to work for more people than Rust in its current state, even if they are a bit fragile.
But it is ok, assuming that Rust's main goals isn't to cover all industry use cases supported by C and C++ in 2022.