The article says the music is played to keep the emergency stairwells empty. If you haven’t lived around unhoused before, they can take up a lot of space with their belongings and can be pretty unresponsive.
Exactly the kind of thing you don’t want in an emergency stairwell.
Honestly if the owners of a building CAN’T keep the emergency stairwell clear then the building should be shut down for everyone for safety reasons.