I think I got it! (SPOILERS!)

I just watched both parts, and I think I understand what ~they~ were thinking : it's NOT Philip Jose Farmer's "Riverworld", it's about about aliens who read PJF's books, were fascinated by it but also had a bit of a weak spot for the Discworld and out of boredom kind of recreated it to play games (think Deities in Dicworld).
They didn't have much in terms of resources, so they only resurrected like 20 humans, and for some reason they disliked the character of Burton, so they made him the black king. they took some random guy from the USA because they had a background in cheesy T Shows and made him the white king, and they also had puritanistic ancestors, so they just ignored all this yuk-y baldness, nakedness and drugs from Riverworld.
The resources shortage also led to a ramshackle "Not For Hire" and a weird looking Zeppelin-like thing with a restaurant but no crew or passengers. (concerning the Zeppelin, one of the aliens thought he was witty, and left a message on it : the name "Rumpfurzen" is telling all the humans how much the aliens care about what happens. It's just a game to pass time. They could have easily been telling fart jokes to each other).
And so, in the (hopefully not happening) case that this turns into a show, the group of people on the "Not For Hire" will always be driving up river, fight against Burton and destroy or save the world, and at the end of the episode all the dead ones will be resurrected to be fresh for the next episode! Yay!


So, it's Riverworld meets Discworld on Groundhog day!

Please let this show die a quick death!