HN algo stripped the "Why" from the original title:

"Why we didn't rewrite our feed handler in Rust"

I'm not a very experienced Rust person, but I suspect the buffer reuse concern could be resolved with a tiny custom allocator, so semantically it's a new buffer on each iteration of the loop, satisfying the borrow checker, but the allocation is free. There are a number of bump/arena/slab allocators that do this, like bumpalo, but it would also be possible to write a small custom one specifically geared toward "just continually reuse this exact pointer".

Anyway, I don't mean to nitpick; I know that what's given in TFA are high level examples representing broader classes of concerns, but I thought this one in particular was interesting for having some decent alternatives.

I wonder if for issues 1 and 2 a small amount of unsafe code could just solve them. At least for 1 this would seem quite achievable.