Good line of questioning Jonng. I have always been told that the name refers to the posture of the abstract figure. One arm goes across the belly and the figure is bent over as if sick to his stomach. But i suppose this jester could just as easily be a bow.
I am not convinced that the Jawa Demam is related to the squatting figures. The body positions appear quite different to me. In the squatting figures the hands are generally on the knees and they are, of course, squatting which i don't believe is the intended body position of the Jawa Demam.