Why are they still nice to this guy at work?

i work in an esl school in korea. a new guy was very nice and polite to all the staff. hes been having some problems with his apartment which is provided by the school and he blames the whole staff. sine then hes been very cold and uncaring towards them,even after they gave him birthday presents.even still, with his rudeness, they are still trying to be nice to him.but he changes to being nice with the students. hes very handsome, and the school could use him. whats your opinion