If you run somebody else's code and you don't trust that person, you need to read their code carefully anyway. Safe Rust code can do all kinds of shenanigans including:
* Wiping your disk
* Downloading and running code from the internet
* ...
Rust's safety guarantees don't exist to protect you from a malicious Rust programmer. They exist to protect you from mistakes a well meaning but fallible Rust programmer can make.