Regardless of whether you have a cough or congestion, airway clearance is one of the pillars of managing MAC and Bronchiectasis. There are many discussions in this group about airway clearance, and why it is vital, but I most frequently suggest that you watch the video by Dr Pamela McShane, one of the foremost experts in managing MAC. You can find it here:

It is possible, if you are asymptomatic, that you can manage your MAC with airway clearance using 7% saline nebs, WITHOUT the antibiotics. A pulmonologist who doesn't suggest airway clearance may not be experienced at managing and treating this rare infection. At our most recent appointment last week, my pulmonologist said she has a number of patients who have kept their MAC controlled for years with saline & airway clearance and no antibiotics.