It was not the u-turn that caused their elimination, they were last anyway and the only way for the Globetrotters to loose from them would be if they had lost their way to the pit stop.
IMO the cowboys lost because they never bonded with the other teams. It was obvious from previous episodes that they kept to themselves, they didn't mingle with the other teams and that lead to their demise.
We mustn't forget that TAR is not only a race but also a social game and alliances or at least good relations can be important. The cowboys didn't have that and that was obvious in at least 3 occasions in this race, a)in Sydney, when half the teams told the others the decoded message, but Jet never even thought of asking for help, b) in the flight from Calcuta to Varanasi and c) in the flight from Varanasi to Austria when the cowboys chose a different fight when they knew that all the other teams were together.
Most obvious example of their aloofness was in this episode when Jet didn't stick with Gary during the RB, if he had worked with him, they wouldn't be eliminated.