This was emotion management. Although the team felt a bit depressed, everyone had to respect Achilles' callous attitude.
Clearly, Achilles wasn't totally inhumane and was fine with the group satisfying basic needs like eating and drinking. However, alcohol would definitely not be allowed.
However, humans often yearned what they were deprived of the most. Dong Xiaosa and Pi Xiaoxiu could barely hold back their desire for alcohol, especially when they were facing a group of people who were gobbling down huge chunks of meat and alcohol. It must have felt so good! Dong Xiaosa and Pi Xiaoxiu were salivating. However, they could only drink mineral water, and this was distasteful to them.