As a Rust user, I think it's fine for the grandparent commenter to link to the I-unsound tag; even if some of those bugs are only accessible on the unstable nightly release, there are plenty of soundness bugs to choose from on the stable releases. The important thing is Rust's philosophy that soundness issues are to be taken seriously, even going so far as to allow backwards-incompatible changes if necessary to address them (though obviously this is a situation of last resort).

There are several people working on formalizing aspects of Rust, and though it will take a long time to get there such efforts have already found and fixed bugs in Rust and its standard library. It's fair to take SPJ's critique on the chin for now; Rust deliberately chose the path of eventual soundness in order to produce a usable language in less time, and as long as we keep working towards that goal there's nothing to be ashamed about.