I am in this challenge(, in Segment [2]).
tl;dr don't fuck us over because you simply want to eliminate the weakest linkI'm under the assumption that this possibility has been thought through by zorbees and challenges will be changed appropriately according to the situation of the setup to keep things competitive.
Furthermore, focusing on one faction initially will often not be enough to win the game, given past games have had their Corleones because once people thought they were weak enough, the other larger factions spent so much continuous effort focusing on each other that they often forget about the 3rd guy. See: GFeds of MP2, Castlevanians of Metroidvania. Also you'd be putting a lot of trust in a faction that would need you dead as well who would smartly see the larger faction as a bigger threat due to maintaining versatility. Furthermore, trying to fuck over a smaller faction is going to ruin both larger factions' chances of winning as they no longer have someone to potentially work with.