I think he has a point about the sloppiness and unresponsiveness of the government -- although the sloppiness and unresponsiveness of a large, bureaucratic organization hardly justifies carrying out his own miniature September 11th! Doubly painful in that the people he killed probably liked the IRS no more than he did -- few workers in government bureaucracy _enjoy_ what they have to put up with...
Killing others and committing suicide are both very serious matters, so I hate to say this, but his rant on the IRS reminded me of nothing so much as Timecube. What have we done wrong in this society, that we get people like this, especially the deadly ones? I don't think it's a political, moral, or social-outlook problem; but I hardly know what it is. A more honest and competent government would have removed this man's particular grievance, but it wouldn't have fixed the root problem; someone in his mental state is probably going to find something to be aggrieved with regardless...