As recall the only reasons people put up for it not being a terorist was that there didn't seem to be a political motive, and that the modus operandi - individual random assassinations - didn't fit with the assumption that terrorits just like big bang spectaculars.

While I think it much more likely it's some screwed up character who's moved up from shoot-em-up video games to the real thing, I can't see how either of those reasons in the last paragraph actually stand up to scrutiny. Causing panic in the capital city of the United States could tie in well with an intention of destabilising things. For the expenditure of nine bullets so far, I suspect more distruption has already been caused than would have been achieved by a bomb. And the idea that terrorist are incapable of methodical patient activities such as this is just nonsense.