Yes, well done for noticing this and taking care to try and keep it safe.
Back in my days at uni, I worked as a campus security guard during the holiday breaks (24 hours on/12 hours off...I met myself coming and going). I ran into a similar situation and after discussing it with my supervisor, we decided to take the bike into "protective custody", cutting the lock and placing it in impound with a special note as to location, time secured, etc and then placed an ad in the student newspaper.
As it happened, the bike was eventually reported stolen two school terms later(!) by the owner, who had to leave school unexpectedly due to family circumstances (illness ending in a death). As soon as the report was filed it was matched with the impounded bike which was reunited with the owner, sans one cut lock which did not matter to the owner compared to losing the (then) very expensive bike. They were only grateful and pleased at our thoughtfulness and actions.
I'm not sure if such action is possible or even legal in your location. I do recall there was considerable concern about whether impounding the bike in an effort to keep it safe amounted to conversion under (US/Oregon) state law (conversion happens when a person intentionally takes the personal property of another or deprives another of possession of personal property without authority or permission. It is a legal tort which allows the injured party to seek legal relief) We ran it by the law school faculty and they concluded so long as the bike was returned to the owner within reasonable time of contact/on demand, it would be okay.
This Nomad is fully kitted out and like you, I am amazed it is still intact. I think Ian's idea of checking the serial against the list here is a good idea that might allow the owner to be found...
http://thorncyclesforum.co.uk/index.php?topic=7767.msg109784#msg109784Best,
Dan.