in my experience many yogic breathing exercises, especially some techniques from kundalini/kriya yoga can lead to these cough attacks like you described if combined with smoking

your lungs get trained to absorb more oxygen, makes them more sensitive

had several episodes in life where i either had to stop smoking, reduce it to one cigarette a day or retain completely from practicing breathing exercises in order to stop the cough attacks

maybe he has the same problems that i had, maybe not