The canto is about action, but also about the hunger of the pilgrim as well as the snails and slugs, hunger for solace, for eternity, or just greed. Dante gets to defend the pilgrim and gets frustrated in the process, having perhaps forgotten what it’s like to have mortal desires.
Dante is expressing his disgust at lawyers just because they defended people who had committed heinous crimes, yet he admits his views are imperfect. There is some bitterness in his voice, having seen these scenes over and over again. Comparing lawyers to thieves is a bit of a clichéd idea, but that is precisely why I deemed it a good topic to explore how morals change. Even clichés can be broken down. In the discussion we again see a clash between the medieval and more modern views, yet it’s not exactly a conflict.
The point is not that lawyers would be evil. Rather, Dante feels the urge to judge the snails, yet he too sees that this cycle of destruction, hunger, greed and suffering, is pointless. If there was once a reason for the punishments the pair sees, they’ve largely been forgotten. All that remains is Dante’s memory and the vague guilt the victims themselves might feel. Now there’s just hunger. Does it really matter what these creatures were like in their human forms?
Dante and the pilgrim find they have a lot in common too, as many questions are the same through the centuries. From this process of comparison and contrast, the willingness to understand each other and find common ground, some kind of friendship is forming that transcends the protector/ward relationship they’ve had.
In the end Dante does hold on to his judgment, his bitterness, but admits that his fury is not a measure of truth. In the medieval world moral absolutes were more easily conceived than today, but it is still very human to think in terms of absolutes when you feel the outrage, and to place judgment as if the strength of your feeling was a measure of how right you are.