To readers and to everyone in the room, it’s clear that the police set Dad up. Moreover, the police are clearly only interested in convicting
someone of the crime, whether or not that person is actually guilty. In other words, they want to look like they’re doing something, not actually carry out justice. And Dad shows that his loyalty is, at this point, to his family: he fell for the police’s trap because he wants to save his family members from death or dehumanization.