Anything you can think of related to the gov't (as well as religion) can be thematic with schizophrenics. Talk of the constitution isn't especially unusual or esoteric in my experience working w/mentally ill clients.
People are leaping to conclusions here.
The main erroneous conclusions being leaped to here are the straw men.
It's misunderstood what the nature of the relationship between the right wing vitriol and the shooter is. For example, showing the example of Palin's crosshairs map is not saying Palin is personally and uniquely responsible for these homicides.
It's misunderstood how the vitriol can be a trigger for this kind of mentally ill person vs a trigger for a zealot like Tiller's murderer.
And finally and most importantly, it is misunderstood that each and every individual reference to a gun or target metaphor is NOT what this is about.
The issue here is not about every single use of any one symbol or word. The issue is the total picture and the responsible people are the Repub leaders who put the themes and talking points out there for the right wing echo machine to repeat.
The right wing has been stoking fear in fringe groups because that gets votes. The emergence of the Tea Party, IMO, is a direct result of this campaign rhetoric tactic. During Bush's campaign and administration, the Repub leadership courted the extreme Evangelical right. Rove discussed this tactic many times saying things like there were a lot of single issue voters that could be stirred into activism over issues like abortion and gay marriage. That's the whole reason those issues have been so overwhelmingly adopted by the Repub Party, not because all Repups are anti-choice homophobes and all Democrats are pro-choice and supporters of gay marriage.
With the Obama win, the Repub leadership has shifted gears and the more recent incessant campaign centers around calling Obama dangerous, a Socialist, and not 'one of us'. The campaign also involves stoking racism against immigrants, and fear that government is going to take over and ration health care. The campaign also includes stoking fear that Obama and a Democratically controlled Congress is dangerous and will dramatically change the government, yadda yadda.
In promoting these campaign lies, what better way to stoke fear than to include over the top rhetoric claiming it is so bad that if it doesn't change, armed revolution could be necessary. That theme is also encouraged by stoking the pro-gun extremists who are already convinced the government wants to take their guns away. The last time I saw anyone making a big deal of carrying assault rifles around in public was when the Black Panther
WP movement started doing it back in the 60s.
It's the Repub leadership promoting the theme of the lie that Progressives or the Democratic Party are trying to radically change the US government and they are dangerous that is the rhetoric of concern here. The issue is not the straw man that the of simply using words like, target, or symbols that look like a target or gun crosshairs on a map.