It's not the director(ies) where the current links are that matter, it's the directory where the new link is being created that should have to be sticky for the new rules to apply.
It even makes sense, because in a sticky directory you can create hardlinks that you can't then remove, but the same isn't true of nonsticky directories.
It's also unambiguous, and the destination directory of the link already has to be looked up to create the link.