The concept of unsafe language constructs are about 10 years older than C's birthdate, written in different forms, lowercase, uppercase, special module to be imported, whatever, all ignored by C's authors.
As for C being low level "assembly-wrapping" stuff, yeah when all you have is a PDP-11 clone.
All my point was that Rust is not a substitute for C, too heavy and complex and not enough liberating for low level "assembly-wrapping" stuff.