I have no idea what the laws are in DC, but as a law major I can safely say that in NY state at least, verbal contracts are binding and what was posted in the OP of the Pound 5 thread, about payouts, can most likely be considered a verbal contract. What must be taken into account though is that we have no actual proof of the final amount of entrants/what they payed to my knowledge, and to be honest, I'm not sure how such a case would hold up in court.
I can, however, tell you this: lawsuits are extraordinarily expensive. In a case like this where Discovery is a critical process the money is gonna add up fast, and regardless of what they tell you "You only pay us if you win!" you're held accountable for their expenses such as discovery and depositions, which cost a lot more than even Dr. PP probably won.
I can also tell you that posting stuff about this here is not helping your case at all if you do proceed with it, which I do not advise.
I don't know how I feel about this whole situation, but I can say that this isn't good for the community either way and I feel bad for all parties involved. However, we have to remember that we're relying on honor rules here. In the end, it's probably going to be up to Plank whether he pays you guys or not, which I hope he does.
That being said, continue to rant, you all have a right to be angry. I'm also not going to tell you to stop with this legal stuff, because that's up to you but I can, as someone who knows enough about the inner works of the legal system from ~3 years of legal studies, advise you to not do so at the cost of your own time + expenses.