Yes, sending a friendly note to github seems like a good idea. But don't expect too much apart from the satisfaction of seeing his current account banned.
This seems a bit over the line. So the elancer has no way to right this wrong? OP should just message the person. If he doesn't fix it then contact the site admins, etc. But hosting code with MIT license as others have already mentioned is permissive. I'm not a big fan of the online witch-hunt when someone messes up. If they learn from it and move on they're still a target and have already been banned forever but what should be an evolving community.
Maybe they just don't understand that you could sue them.. and that, if they broke the terms of the license, you would almost definitely get all of their profits if it were successful.