Re: changing languages isn't going to fix this.
No-one is claiming that Rust will eliminate bugs.
The claim is that Rust will *reduce* the number of *exploitable* bugs. Because a whole class of usually-exploitable bugs change from being "very easy to write unless you're incredibly careful" to "impossible to write".
There are other classes of exploitable bugs (e.g. missing a permission check) that can be done in any language. However, if you have code review, the reviewers don't have to worry about memory bugs so can spend more time looking for other bugs.