"Blocks" are relevant as they are how you express programs, algorithms, etc., that you need in order to get something done. Lots of data structures in Rust have a little unsafe somewhere. Users will typically depend on some "specialist" crate author to write them, but it exists, and is a necessary part of practical Rust programming. The pool of unsafety is open and by necessity growing.

In Fil-C, no such specialists are needed, and the pool of unsafety is closed and fixed, no matter what programs, algorithms, data structures you use.

This is not a trivial distinction I think. I think it's easy to acknowledge, especially given its (current) performance cost.