Now that I think about it, people are probably worrying way too much about someone else registering with Nadeshiko. Pretty sure no device with a fingerprint reader automatically registers the first person to touch the reader without running the proper protocols, surely a much smarter Nadeshiko can ensure there's no forced registering done either.
Unless it's a one time thing in which case it wouldn't be a particularly sophisticated system since it would only need to be used once
Surely even then there would be anti-theft measures in place, at least to avoid her getting "misplaced" during delivery?