I am attempting to mediate this. The goal in any mediation is simply to try to get the parties to agree to something. Who's right, who's wrong - none of that matters and in fact, these stances work against the process. Facts don't matter. Often a mediator has to play both sides and juggle the facts. The goal is to nudge the parties to an agreement using any means available.
Let's face it, when people take a stance like "I'm right, they're wrong" you're not going to get anywhere. Even if something is morally right or factual, it works against the process of coming to an agreement that both parties love and/or hate equally.
Not long ago, I had to hire a professional mediator for one day. The cost? $6,000. She was able to bring both parties to the table, and bring their ludicrous, far apart demands to a settlement- she was incredible and well worth the money. She was able to do this because it was in everybody's interest to settle up but she used every trick in the book to make that happen. She shuttled from one room to another for 8 hours until she arrived at a settlement. I honestly didn't think it would happen.
My personal opinion doesn't count. FYI my personal opinion is, matching up like this over an internet argument was a crazy notion in the first place and I stated that in a previous thread. Mediators are not immune to their personal feelings. I am sympathetic to the fact that John lost 10K. For that, I believe he has the right to ask for some reasonable concessions, although the way he placed his non-negotiable challenge was doomed to failure if he really wanted to play.
John and Lou do not need to play. They do not need to settle. They either want to play or they don't. My feeling is, at this point, they don't seem to want to come to an agreement. So be it.