But the point here is that he is not "unmotivated" to do his regular job (she makes no mention of that), he just doesn't want to do the free extra time on night

But the point here is that he is not "unmotivated" to do his regular job (she makes no mention of that), he just doesn't want to do the free extra time on night and week end for which he was never paid with to begin with, but used to do out of "volunteering" (her own words). You can't fire a guy and then expect him to be 100% motivated, but you can even less expect him to keep doing the little extra on the side just for you ...