How did the thanos of the infinity ultron universe aquire the soul stone without gamora telling him where it is let alone sacrificing Gamora who at the time was at the sovereign place with the other guardians.
Who says it had to be Gamora to be the Soul Stone Sacrifice? In the Ultron Infinity universe it could have easily been Nebula instead who was his Favorite Child and Thanos could have Sacrifice Nebula instead of Gamora?