The specific point about nightly isn't about Rust per say. It's more about using what is essentially a development version of a compiler, updated nightly. Explo

The specific point about nightly isn't about Rust per say. It's more about using what is essentially a development version of a compiler, updated nightly. Exploits aren't necessarily even the biggest threat. Nightly could have bugs, and in the context of cryptocurrency, compiler bugs can mean large amounts of lost money.