Few airborne particles from building materials are ok for people to inhale, so you should always take precautions regardless of whether its recycled paper, crystalline silica, or asbestos.

Good practise would be to use plastic dropsheet to quarantine the area so he can keep the dust contamination as close to zero as possible. He should also be wearing a p3 respirator to keep himself safe. If water suppression is possible, use that. He should also remove his dusty clothes after finishing up and put them in a plastic bag to be washed separately.

While its only one wall, and everything will most likely be fine, workplace lung diseases are not to be taken lightly. I learned the hard way.