Presuming what I found was his suicide note, he was basically a guy who had life jerk him around one time too many. The IRS was a target because of policies they enacted that basically ruined his career (well, him and others in the same line of work). There was also a matter of an incompetent accountant getting him audited (which is it's own version of hell from what I hear).
I sympathize with his pain, but this wasn't the way to deal with it.
The contents of his suicide note actually make it plain that he was a longtime tax protester who subscribed to a well-known bogus interpretation of the tax laws that he claimed made it unnecessary for him to pay taxes. For those who are knowledgeable in US tax protest arguments, it is called the "Section 1706" argument. It does not deserve a hearing on these forums.
His situation was entirely of his own making, and he deserves no platform for any claim that his distress was caused by an oppressive government or an incompetent accountant.