"Initial police accounts had indicated that the man had a sign supporting Obama, but witnesses later said it was an anti-Obama sign with a Hitler mustache drawn over the president’s face. "
Lurn 2 reed.
Really, the article makes it perfectly clear that it is unclear whether the victim was pro-Obama or against him. Which makes the political orientation of the attackers (sorry, 'alleged attackers') questionable. But then again, what does it matter -- it doesn't.
I would allege the 'extremism' lies in the actions of those who did the violent act, and in the opinions and prejudices of those who would assign the act to persons based on political leanings. And do so with incomplete information. Yes, extreme.