I agree, however, the definition of preferring A to B that he gave was choosing A over B (and if we don’t specify that A and B must be total world-states, then it would turn out that I prefer Mexican to Italian because I chose Mexican over Italian). Psy-Kosh’s comment above explains why that isn’t what he meant.
Your example only shows that your preference ordering is:
“go to an Italian restaurant with friends” > “go to a Mexican restaurant with friends” > “ditch my friends and go to an Italian restaurant alone”
I agree, however, the definition of preferring A to B that he gave was choosing A over B (and if we don’t specify that A and B must be total world-states, then it would turn out that I prefer Mexican to Italian because I chose Mexican over Italian). Psy-Kosh’s comment above explains why that isn’t what he meant.