In the context of the hypothetical physicists, it does not help them resolve their confusion to point to the hand shaking. Their mistake is in only counting the work done by the hand to the object. Once they've made that mistake, telling them that the hand shakes would not change their minds, since it doesn't show net work being done by the body in that respect, which is why I made the comment you quoted.

The mistake could only be corrected by pointing out the incorrect model of how humans generate lifting force.

So while your point is correct, and perhaps obvious, one should also remember that it doesn't address the specific mistake I criticized.