spec.linkAccess is expected to be a no-op for system sites, where RouterAccess needs to be created manually.
However, setting it to default causes system sites to be stuck in status Pending.
This happens regardless of the RouterAccess being created or not, and does not impact the operation; despite the Pending status, the site is able to accept incoming connections and participate on the VAN (when the RouterAccess is also created, of course).
This has been tested on both podman and linux sites, so it does not seem to be platform-related (other than being non-kube).
There is a reproducer at https://gist.github.com/hash-d/33c1186c9f91cb3311718a9ecdceeedd.