Two political issues were raised in the interview: the filibuster and public housing. Although these topics seem unrelated to medicine, I think there are two possible reasons for including them.
The first possibility is that these questions test whether candidates care about public health and matters that affect Hongkongers. They assess candidates' understanding of a broad range of social issues, and their analytical skills.
The second possibility is that such topics test independent thinking. Someone may be very intelligent, but unable to think for themselves. They may have applied to study medicine because it is expected of them, not because they have a genuine interest, or because their parents and teachers recommended it. If they are not genuinely interested, or naturally talented, they may drop out of the course.
While at first such issues seem unrelated, I think it is important to test candidates' attitude to social issues. In healing patients, they will contribute to a healthier society.