A scan of my blogroll and Facebook feed suggests that most libertarians tend to agree with conservatives that the Giffords shooting does not have implications for the supposedly high pitch of contemporary partisan politics. See here, here, and here, for examples.
Why is this? One simple explanation is that most libertarians are more sympathetic to the Republican party in general, and the Tea Party in particular. I suspect that most American libertarians come from the right. It is certainly true in my case.
So it could just be partisan bias. A more sympathetic explanation is that libertarians are all strong individualists. Individualists tend to want to compartmentalize moral blame. They want to blame only the person who actually commits a bad act. To do more would question the self-responsibility of that bad actor and impinge on the autonomy of other actors. If you loan your roommate a copy of The Road to Serfdom and he bludgeons his congressman to death with it, neither you nor Hayek is responsible. Even if he got the idea from reading the book. This is how I tend to see things.
Progressives are more sympathetic to the notion of shared responsibility – which they sometimes refer to (in confusion, I think) as “personal responsibility”. Viewed with at least a grain of determinism, it is not in fact true that humans have complete willful control over their own actions. Human actors are influenced by their environment, including the actions of other humans. If you give your friend alcohol and then he has an accident while driving home drunk from your house, perhaps you share some culpability? But it is hard to engineer a solution to collective responsibility, even if it is real.
Conservatives tend to share the individualistic outlook but I’m not sure how consistent they are. If a Muslim person committed a terrorist attack in the name of Islam, many conservatives would blame “Muslims” or at least “Islam”. Would libertarians? Progressives would be less willing to assign collective responsibility to Islam. Perhaps because they are used to thinking of government, not religion, as the relevant collective. Or maybe because they are not a part of this particular collective? Or perhaps they have a complicating commitment to cultural sensitivity.