The reason why the AI version of Polystralia wins a lot is more complicated then that.
First, Hutama is weighted towards achieving one of the victory conditions as fast as possible (less than Rejinaldo, but more than Elodie and Kozlov). KP, PAC, ARC, and PAU take a lot of detours.
Second, Hutama has the highest bias towards Harmony (on par with Elodie, more than Kozlov and Rejinaldo). Outside of lucky progenitor ruins, Harmony has the quickest victory.
Third, Hutama has the highest bias towards expansion (on par with Elodie and Kozlov, much more than Rejinaldo). The top AIs in every single Civ game has always been the ones biased towards rapid expansion.
Fourth, Hutama has the highest bias towards exterminating alien nests (on par with Kozlov, and more than Elodie and Rejinaldo). If the AI likes to play nice with the local animals, they're going to have a hard time expanding.