There is truth in this, but I'm not sure whether the reader can/should extrapolate this to larger situations (not that the author implied we should, but it was my first interpretation).
We know that in certain situations, borrow checking works really well and allows us to guarantee safety with minimal friction and no overhead.
But there are other cases where safety and performance _are_ in contention, and we must choose one or the other. Anyone who has been forced to satisfy the borrow checker by using a .clone(), using Rc, or refactoring objects into a hash map and referred to them by an ID (that must be hashed to exchange with a reference), has felt this contention. In https://verdagon.dev/blog/myth-zero-overhead-memory-safety, I concluded that there's no general approach that always has zero overhead, at least not yet.
So perhaps the best interpretation from this study is that often, for small enough programs/areas, there is no conflict between safety and performance.
For larger programs with more complex requirements and data interrelationships, the question becomes much more interesting.
> I see no reason why a straight port from Rust to C++ wouldn't have been possible while satisfying their requirements.
Like the author, I also don't see a reason for this, but I've never tried myself. I've always thought that with the restrict keyword, one could make any C++ as performant as any Rust code. Perhaps something else got in the way there.