Sure, you have to go back to his rookie year. Sure, the YouTube results for "kirk hinrich dunk" are pretty embarrassing. Sure, 82games.com has his dunk attempts at 0.0%. But if you go to the 50 second mark in the above clip, there is video evidence of Kirk Hinrich dunking in an NBA game. In fact, the dunk was so good, Interpol named a mediocre single after it.
Of course, Hinrich used to dunk all the time in high school.