Rust has stopped depending on closures for async when it moved from experimental futures library to built-in async/await. Rust now easily supports mutable and temporary references in async blocks and across await points.

Rust still doesn't support use-after-free, so you can't reference a temporary object and use it in another thread that will outlive it :)

In TFA the second do_work_and_then() example doesn't compile, because it has a UAF vulnerability that borrow checker has detected and prevented.