Either he is a dumpster diver (probably) and not the brightest one of all time or the stupidest identity theft crook of all time.
But it is good news he is looking at others. Id let him be. He'll think you are the asshole if you confront him. Why make enemies. Just dont put nothing good in there. Sucks tho a bit I understand.
He'll go away fairly quickly. That occupation (diver or crook) doesnt usually last.