Not that I don't believe, but can you provide a citation for that fact about Rust in parallel mode? I don't follow Rust too closely, but I hadn't heard of that. That is really interesting.
It is also guaranteed by ownership system: in the safe mode (which is default) rust will statically (at compile time) ensures that a value can only be mutated at a single execution point. It is done by moving, instead of copying any value _by default_, unless it is wrapped in some kind of synchronization primitive or implements a _Copy_ trait.
Synchronization primitives themselves are implemented in unsafe mode, thus limiting the unsafe code scope and allowing custom unsafe code which can also be wrapped in safe interface.