Pretty sure it's because he knows about the palliatives, or at least has a hunch that the Doc did continue some research and was able to develop it a bit. If not the palliatives specifically, he definitely thinks something's wrong with the water.
I enjoy how humane Kanoh Agito has become, I like his slight show of emotions through his small changes of facial expressions, and how he cares for Gaoh Ryuki at the end there