Why would a project need to become "idiomatic Rust" for a Rust port to be useful?
Code size after transliteration is a race the target language can seldom win; abstractions that also exist (or close enough) in the target language get translated 1:1, abstractions which don't get broken down 1:n, and abstractions which exist in the target language but don't have analogues in the source language generally don't get used at all. It's hard to end up with a shorter program following this approach. Only boilerplate with redundant repetition and ceremony - code which has little functional effect other than to satisfy declaration order rules, symbol visibility and so on - can get eliminated.