(1) It's mostly liquid, and what's not liquid (tofu and green onions) is very soft.
(2) It has lots of protein (tofu again).
(3) And unlike almost everything else that's soft enough to eat when your jaw is all ouchy, it's salty, not sweet.
You can even eat it for breakfast, if you're feeling sufficiently nippophilic.
(Cheap store-brand pudding cups are also very good.)