Sarge is looking back and forth between the siblings, imagining rusty cogwheels in his head moving around. There is probably dust involved, too. But he sees the way Rodeo tenses up and after nearly a lifetime spent together - not counting little government enforced breaks - he can read his best friend fairly well. His best guess is that Addie's explanation was lost in translation and he would like to explain it but doesn't want to in front of Addie. It already feels ten shades of weird standing here so he tries to convey everything with a pointed stare. Raised eyebrows. Trying to somehow become a telepath and sending a message along the lines of you got it wrong. Idiot. Maybe it helps. It likely doesn't.
Then there is the very welcome distraction of Addie's explanation for their meeting and somehow he is catapulted back quite a few years when he used to lift her onto the counter of their kitchen for some eye to eye straight talk. There are no counters in sight but he doubts that would be appreciated anyway. "That's all?" Because he doubts that Addie would risk meeting with just any common criminals to help out some cop. At least the one he knows. So naturally he assumes there is some romantic involvement and he sincerely hopes there is not because that would lead to... oh he actually hopes there is. He begins to make a list of things he and Rodeo could do to the guy.