True, but not sure how it's relevant - you don't need memory corruption for the test to perform arbitrary I/O. And even if you trust the tests to not do anything bad, you don't need memory corruption for this to be an issue - any bug in the code emitted by the compiler could cause bad things to happen.

But all of this is ultimately completely unrelated to the concept of "unsafe". You can delete your home directory just fine in safe Rust/Go/Python/etc. You can write a compiler that emits broken code in the same languages; even in a 100% pure functional language with 0 side effects and a perfect bug-free implementation.