Oh please, this umpire has been controversial since his first match. Just because Australia hasn't been at the end of it doesn't make him a just umpire. He clearly has something against S Asian teams. I didn't believe at first, but after reading this article on BBC I'm starting to wonder.
http://news.bbc.co.uk/sport2/hi/cricket/england/5271108.stm
And please, Imran Khan didn't literally mean that he is out to kill people, you know what he means. He's a stubborn person, that's what it means more or less.
Pakistan felt that they were innocent, which is exactly why they chose to protest, instead of accepting a 5 run penalty and therefore accepting that they did tamper with the ball.