Hostile, belligerent rhetoric isn't wrong for what it causes. It's wrong for what it is in itself.Read Poniewozik's whole piece here.
There's already a reason that it's inappropriate to use "fight" and "target" and "battle" metaphors cheaply; to suggest "Second Amendment remedies" for frustrations at the ballot box; to put crosshairs or bullseyes on a map over the districts of your ideological opponents; to make a campaign ad where you take out a rifle and shoot a bill you don't like.
That reason is not that somebody is going to see that and suddenly decide that murder is a legitimate means to an end. It's that responsible, grown people don't act that way in public. It's because it cheapens us. It's because acting as if every triumph of your political opponents is the end of democracy, every concession of your allies the appeasement of Hitler and every election loss a secret coup is bitter, small and ugly. (No one inscribes the monuments of beloved leaders with their greatest political insults.) It's because our automatic habit of seeing every disagreement as a "battle" with "targets" and "war rooms" makes us a cynical, depressed, crabbed electorate--at minimum.
If Jared Loughner were somehow definitively proved to have acted for reasons entirely unrelated to violent political rhetoric, would that violent rhetoric suddenly become any better? No.