STRATFOR discusses Jared Loughner, Re. Giffords, and the whole issue of Congressional security and protection. The article notes that all evidence so far indicates Loughner acted completely on his own, that he had been acting increasingly erratically, and that he had apparently been nurturing a hatred of Giffords since at least 2007. (As detailed, Loughner had attended a Giffords public event in 2007 and "asked an odd question about semantics". Reading between the lines of other reports and comments about Loughner, this is presumably the question that Giffords did not understand — possibly, given his ravings on YouTube, because it made no sense whatsoever¹ — and this may have been the point at which he decided she had to die.)
 Which is to say, judging by his rants about government mind control through controlling grammar, the odds are good the question was completely batshit.