According to what is being reported it seems that one, he exceeded his alloted time, Kerry asked to answer the question, the police seemed to ave their own protocol when dealing with people who are being unruly, Kerry claimed not to have known about the taser incident till afterward.
Seems to me that he was looking to make a splash an was expecting the out come. Just a wag on my part but wen you get 4 cops around you and they are looking to get you out and you resist them, the result is pretty much a forgone conclusion at that point. Not sure what else he is expecting.
A for Kerry, he seemed to want to answer the question but there was little he could do sine the cops were already involved.
Not sure what GW incident you are referring to but the secret service would have done the same thing IMO if it even got that far.
More here:
http://www.cnn.com/2007/US/09/18/student.tasered.ap/index.html#cnnSTCText