It's also pretty amazing when rightists counter genuine concerns about far-right terrorism by pointing to groups like Earth First, who as far as I know set SUVs on fire at their very worst. There's a word for this rhetorical trick in Icelandic, "smj?rklippa", loosely meaning "to put butter in a cat's fur." You divert attention away from a problem by making people focus on less serious, often unrelated problems (the metaphor being that the cat is too busy trying to lick the butter out of its fur to bother you anymore).
And that's what really bothers me about this. The GOP has been reluctant to condemn these extremists, because they're their base. So instead of having them call for reasoned and rational discussion of the issues, or just condemning extremism, you have them going on the defensive when someone murders an obstetrician with some "well, what goes around comes around" bullshit, and jumping through hoops of logic to defend bringing loaded guns to political rallies. The party is lost to these idiots, and has been for a long time now. When Mike Steele feels compelled to apologize to Rush Limbaugh, something's very wrong with who's running the show there.