Technically, I would agree that he's not contractually obligated to pay anyone back, because I'm certain no one actually signed any documents. ...
First sentence already shows a fundamental lack of understanding contract law, this is simply not true. Contracts can be of any form, and are there to be kept. Proving it to a judge is another matter, but not impossible.
Actually I understand contract law pretty well which is why I doubt that any of hashking's 'contracts' are enforceable. A couple of emails or forum posts back and forth are barely more credible than an unwitnessed oral contract. Hashking also claims to be 15, which makes contracts nonbinding on his end, since under-18 year olds don't have agency in the eyes of most courts anyway.