I also think that doc page is a little old. The feature is over 2 years old now and hot reloading is inherently "unsafe" in any compiled language. It's just letting you know that Rust's safety guarantees might go out the window if there are bugs in the code that handles hot-reloading.
Funnily enough, Mojang is on that list, and I remember recently watching a video[1] of Notch hot-reloading code while developing Minecraft, except it was with Java and I'm sure he didn't pay a dime for the ability to do that.
I also think that doc page is a little old. The feature is over 2 years old now and hot reloading is inherently "unsafe" in any compiled language. It's just letting you know that Rust's safety guarantees might go out the window if there are bugs in the code that handles hot-reloading.