Why are the two policemen laughing at the newlywed couple?Ha Jin's Saboteur

In Ha Jin's "Saboteur," as Mr. Chiu and his bride have
lunch before the Muji Train Station where they plan to board a train home from their
honeymoon, two policemen sit at a nearby table, laughing and joking.  Every once and a
while, the heavy middle-aged policeman, who laughs as though he tells a joke to the
younger one, peers at the newlyweds.  Then, the stout policeman gets up and comes over
to the Chius, throwing a bowl of tea at their feet.  When Mr. Chiu asks him why he has
"tortured us common citizens," the policeman tells the other, "Let's get hold of him!" 
They cuff him and arrest him, ignoring the complaints of
Chiu.

Later, when Chiu is taken to the Interrogation
Bureau, he is again accosted by the middle-aged policeman who has arrested him; the man
grins at him and points his finger and hand as though he were firing a pistol.  Clearly,
the policeman wants to intimidate Mr. Chiu.  Previously, when he and his younger partner
glanced at Mr. and Mrs. Chiu, they have probably felt resentment toward Chiu as a
university professeur.  For, the young officer accuses him of being a "saboteur of the
public order."  The interrogator, too, makes the comment, "We have seen a  lot of your
kind" after Chiu makes the desparaging remark, "Don't mistake me for a common citizen"
when he speaks to the "donkey-faced" chief of the bureau.  In this scene, there seems to
be a class conflict.