I assume any "nightly" version would work in this context, meaning it would not refer to a version from a year ago, as it would have already been made stable by that point, right?
A lot of people pin a specific nightly since the feature they're depending on could change (or ostensibly it would be in stable), so they can keep working without continuously having to track nightly changes or deal with it breaking on a different system with a different nightly version.
That obviously only works for non-library uses of nightly.
"nightly" versions also allow to use unstable features, and unstable features may remain so for a very long time (potentially forever) without breaking, so an old nightly could maybe work