Kerry was trying to prolong the "towering over Bush" moment.
He does the grab, push, squeeze, abuse thing to Theresa and other around him. He is a bully.
BTW, Lyndon Johnson was very well known for this, as well, from his years as Senate Majority Leader. He practically physically forced Senators to vote the way he wanted by grabbing them and just hanging on hard while he was verbally lobbying them.