No. For one it is not that major by the sounds of it so no need to drop everything. Secondly just adding in external rotations is a terrible idea. People with rotator cuff issues have to work on scapular stabilization and that means a lot more muscles need work. The serratus anterior, mid, lower and upper traps need to function correctly, rhomboids and then the supraspinatus, infraspinatus, teres minor and subscapularis. The lats and teres major should need soft tissue work and stretching as well as the Pec minor (especially) and Pec major.
And that is just the start, without a proper assessment.
If something clicks that is never an issue UNLESS it clicks AND hurts at the same time. Don't give rehab advice unless you know what is going on and then only if the issue is completely certain. Telling him to stop if it hurts and go see a physio would be the best advice you could give him.