what i think is, they just want to find a place for them to stay and they discovered that Empire is the best one just like DT Vancouver. They know that police will not come and the Mall manager don't care what they are doing there...
See, when they put message that "F the Chinese", if that stairs have no traffic, what is the point to put those messages? They are just "rats" and for sure police said that what they are doing are not hurting anyone.