I would certainly give back the land immediately. That is the "binding" part
. If Llamabeast came back and said "sansanjuan.. per the text in this PM thread and according to my experience in D3, you had a NAP with Arco" case closed. That goes for any reparations too. Even "Utgard is now AI". I'm surprised you didn't make a similar arbitration request when you were given gems but did not provide an item...
Your other option is to post our *entire* exchange and let the community decide. That would not be "binding" since unlike Llamabeast the players may have biased opinions.
Whatever happens... remember, unlike RL we are playing a *game*. Take setbacks like a man. I've given you two options. Present your case without rancor.
-SSJ