Anakin wanted to refute that 'dubious' remark, but Obi-Wan's demeanor change stilled the fight in him.
He reached for Obi-Wan as the man moved past, his hand coming to rest on the man's shoulder. He wanted to say he understood - oh, did he understand how emotions could stir a person to action in ways that made one feel foolish later. That was a theme Anakin played all his life.
You had to confirm it, I would have done the same with Padme. He projected it, not wanting to expose Obi-Wan to more embarrassment in front of Siri.