Juan Cole nails it.
Think about it: when you watched or read about the shooting in Colorado or in Texas over the last few weeks, did anyone ever utter the words terrorist? Thinking on it, the last time we really spoke about domestic, homegrown terrorism was McVeigh (save for Obama annoucing his canidacy at Bill Ayer's place and the totally unnecessary shit storm that started). These people are no different, we just call them something different to make ourselves feel better.
In the same way we're subject to becoming victims of terrorism, we're at the same, if not greater, risk of being terrorist. Try ammending gun rights and watch what happens.