I would think that no, that would not be allowed to be implemented. If that was implemented anyone could just go and simply unclaim a town plot to steal anything in a chest that was on that plot. Not a very good image to me.
The reason us mods have to be the ones to unlock the chests (Other than the person who they are privated to of course) is so that we can judge whether the chest is allowed to be unlocked or whether the chest should stay locked because the owner of it still has a right to what's inside it. It makes it fair and gives people security that their items won't just be taken at any moment when they're not there, or even if they were on the plot.