Why do heavy metal guitar players dislike President Obama?

Back in April, we did a post about how Ted Nugent does not want President Obama to be re-elected.  The Motor City Madman is not alone in his anti-Obama views.  The Onion AV Club posted video of Megadeath leader (and former Metallica guitarist) Dave Mustaine explaining to an audience in Singapore that President Obama "staged" the recent shootings in Aurora, Colorado and Oak Creek, Wisconsin so that President Obama's administration could "pass a gun ban."  Mr. Mustaine did not elaborate on how such a measure would get through Congress.  Nor did Mr. Mustaine explain how such a ban, if passed, would survive an inevitable Supreme Court challenge.  For that matter, Mr. Mustaine does not explain how the shootings were "staged."