He first got interested in animal rights in high school. During a class called "social justice issues," he decided to give up eating at McDonald's because he says the company encourages ecological destruction. That led to his disavowal of eating any kind of meat, which led to his interest in progressive authors like Noam Chomsky and Peter Singer.
What a surprise, that he's into such deep thinkers as Chomsky and Singer. Looking at that picture, I stand by my assessment on the other thread - "spoiled little white-bread suburbanite bastards"...
Bet they won't take the hypocrisy challenge: Swear they'll never take a medication or submit to a medical procedure that was tested on animals.