Not being aware of how vulnerabilities are detected and despite being a big fan of Rust, I wonder if there are other variables that drive down the ability to find bugs in the short term. If a researcher is only familiar with C and C++, is it possible that they're just ill equipped to find similar bugs in Rust?
That said, there are a ton of ways that auditing for vulnerabilities is just as easy or way easier. In particular, most tooling for C/C++ can be applied to rust - fuzzers and sanitizers, for example. Additionally, one only has to "grep for unsafe" and work from there to find Rust vulns, which largely amounts to "what are the assertions for this unsafe block, are they complete, are they held?".