[deredede]

From the horse's mouth (article of the linked HN post):

> PL/Rust contains a small set of lints to block what the developers have deemed the most egregious "I-Unsound" Rust bugs. > [...] > Note that this is done on a best-effort basis, and does not provide a strong level of security — it's not a sandbox, and as such, it's likely that a skilled hostile attacker who is sufficiently motivated could find ways around it (PostgreSQL itself is not a particularly hardened codebase, after all).

They have extra lints to help you avoid what they deem the most common soundness bugs. They make no claims that there is a way to make this approach safe against an attacker.