I think you're mixing up tail recursion with general recursion. Rust absolutely supports recursion: the implementation uses segmented stacks to allow for stacks to grow dynamically. Tail call support is about not having the stack grow but only in the subset of recursive calls that are in tail position.

So support for tail calls is not about safety but expressiveness, and Rust chooses to express iterative algorithms through other means, such as the iteration protocol that's built on top of higher-order functions.

EDIT: Maybe I'm misreading you and you only mean the imperative nature of loops forces you to use mutation. Rust does not eschew mutation altogether. Even as a functional programmer myself, I'd argue pretty emphatically that mutation, particularly of local variables, is not a grave safety concern.