I think the Rust standard library is actually a liability in this case, not an advantage. The rust stdlib will essentially be an extra dependency and also the rust standard library doesn't have allocators, so unless you are very careful you might violate the principle of not doing allocations for the user. Also, even if it did have allocators, passing allocators from to Rust via a C interface would probably be awkward.

So if you do choose to make the implementation in another language, there are extra considerations that you have to take into account.