Sokka admitted that tact wasn't his strong point.
So maybe he didn't understand Aang's disgust for the change in the temple. Maybe he was too fascinated with the Mechanist's brilliance to really care what the temple had been.
But it upset Aang, and what upset Aang upset Katara, and Sokka . . . Sokka tried not to care, but unhappiness was contagious.
So later, as Aang sat curled in a ball, staring dejectedly at the pipes bursting through a century-old mosaic, Sokka leaned over and put a hand on his shoulder.
Aang smiled weakly, saying nothing – but words weren't necessary.
