sarcasm 1 : a keen or bitter taunt : a cutting gibe or rebuke often delivered in a tone of contempt or disgust

The overall tone of Part II of Learning from Las Vegas is not one of contempt or disgust.

For example:
"Many people like suburia. This is a compelling reason for learning from Levittown. The ultimate irony is that although Modern architecture from the start has claimed a strong social basis for its philosophy, Modern architect have worked to keep formal and social concerns separate rather than together. In dismissing Levittown, Modern architects, who have characteristically promoted the role of the social sciences in architecture, reject whole sets of dominant social patterns because they do not like the architectural consequences of these patterns."
--p. 154, 2nd edition

This sounds to me like solid critique rather than contempt or disgust. And the whole texts reads more of solid architectural (because the text really is so rich with just talking about architecture) critique then some sort of sarcastically based evil plot.