Presumably the Wisconsin governor meant to show off the bigness of his hand, and particularly the freakish bigness of his thumb. His hands are apparently not only bigger than Trump’s, which have been the subject of much discussion on the campaign trail, but were also about to be employed in the hard work of governing, something Trump knows nothing about.
Of course, this picture gives us no accurate idea of the size of Walker’s hands. His use of forced perspective makes his thumb look huge, a trick right out of the Anthony Weiner playbook. We need an object to compare it to, like the pen he used. Until then, no one can be declared a winner in the battle of the hands.