I ran into some dialogue in San Brahmin (doing tree-pass) that involves low int dialogue. It forced me to analyze this area more thoroughly.
Fallout Sonora certainly has a gradation of dialogues that open up according to intelligence, however, I would say it is imperfect, and could certainly use a polish in the future. The high and low ends in particular are not well tailored to, though the middle ranges are.
The low int path needs the most work, but that would also require a 'goal' first.
Should there be a low int dialogues everywhere? Should low int restrict your access to areas of the game/dialogue, or should pathways be open with stupid dialogue? Or should the low int path really be a dead end, which teaches the player to not choose super low int (an approach one of the original developers espouses I believe, when discussing Fallout).
I also found that the engine injects a choice (which exits dialogue) if the int check fails for all dialogue choices, which means a full low int path with auto answers could be implemented without rewriting every dialogue. Of course, this would certainly lean towards a path that makes you re-roll a character.