In April, my wife Nicole ended up having shoulder surgery to repair a torn labrum, frozen shoulder, and a nearly detached bicept. As a result of this procedure and recovery, she currently isn't able to rock our son before his naps. Since I work from home a majority of the time, this task has fallen to me each afternoon.
From my experience, toddlers maintain the urge to fight nap time, regardless of their level of fatigue. In fact, the more exhausted they are, the worse the struggle. After some amount of time, though, the resistance gives way to acceptance. He is not in tears or upset, just resisting taking a much needed break from an already long day.