No, they should get their full salary, as the author is. The overtime complicates things, I'd personally lean toward including the overtime pay they were projected to have earned to avoid creating the chilling effect you describe (either in perception or reality), but I can see the case for excluding it too.

It's more than overtime, see:

"since half of my income from the University comes from clinical revenues generated from seeing my patients, supervising resident clinics, and engaging in weekend and holiday on-call duties. So while on leave my salary is significantly cut. Furthermore, my contract stipulates that I am not able to conduct any patient care outside the University..."