It is correct. Rust prevents all data races at compile time, unless you write incorrect unsafe code. This is why people try to write as little unsafe as possible. This has nothing to do with Mutexes; mutexes are provided by the standard library and the language knows nothing specific about them.

I understand. It is actually kind of easy to comprehend by remembering the borrow checker will only allow one single mutable reference at a time.

Rust compiler forbids multiple threads to access the same memory location not protected by a Mutex.

That is, only when said memory location is accessed mutably. Immutable references are perfectly ok to follow concurrently.