This is about a strictly-enforced form of run-time memory safety where there's no `unsafe` escape hatch that a careless programmer can misuse to undermine the memory safety mechanism. Contrasting with Rust is helpful to get that point across - which the body text of the issue does.
I can't speak for Andrew, but I didn't read this as a "diss" at all.
I can't speak for Andrew, but I didn't read this as a "diss" at all.