Thanks, xise. It seems clear to me that Ra were referring specifically to how the particular STS entity in the given situation took advantage of Carla's unique preincarnatevely programmed distortions, including apparently a distortion towards wholehearted love at any cost, and by blocking the wisdom from the indigo which would have presumably added a degree of moderation to her activity levels, led her to exhaust herself physically and, thereby, make the physical "vehicle" less efficient/usable.
I wouldn't take this to mean that this example is a characteristic pattern of STS behavior - it seems that it was simply the best available "hook" that they could get on Carla, given her wholehearted STO dedication.
I wouldn't take this to mean that this example is a characteristic pattern of STS behavior - it seems that it was simply the best available "hook" that they could get on Carla, given her wholehearted STO dedication.