I'm in over my head trying to understand recent Chinese history, but I'm just trying to find correlations with Kelly's point of view. Graphically Mao is portrayed as a sort of Happy Buddha with a military cap. Below, known as a Mao cap, it is an obvious icon associated with the man:
Running around wearing a towel could partly be connected with a Happy Buddha image, but I wonder if it might be associated with Mao's famous swim of the Yangtze River in July of 1966, when Mao was 73:
The swim was part of the launch of the Cultural Revolution, and an effort to convince the world that he was indeed still alive, and was a force to be reckoned with, as he was reported to swim 9 miles in 65 minutes, accompanying 5000 young swimmers in the annual race across the river.
Seeing the chairman in the almost altogether * maybe * sparked Kelly's notion of a costume for the caricature? Maybe not, but it was in the news around the time Kelly would have been drawing these strips.