>> Kaczynski's manifesto functions primarily as a rationalization for his violence and anger.> this isnt an argument.
No. It's an assertion. You're free to disagree. However, if that assertion is true, then there's no reason for techno-optimists to bother with his text.
Also, it is an assertion that we can reason about at least somewhat independently of the text. We can examine how the text was written, the manner in which it was disseminated, the reason for its cultural weight, etc.
> either the text is sound or it isnt
That's the point. Reading the text for the purpose of determining whether it is sound will be futile exercise and a waste of time. In the same way that reading Harry Potter as a religious text would be wrong (not morally/ethically/politically/etc. wrong per se, but rather simply and plainly wrong in the sense that a literary analysis can be incorrect).
lucideer's post addresses this directly and ultimately concludes "Overall, the manifesto is not worth reading". I would simply add the qualifier "...unless you proceed from the understanding the the author is a sick man". In other words, it's not worth reading just because you're a techno-optimist. It's perhaps worth reading if you're interested in terrorism or mental illness.
> either the arguments are presented clearly from first principles with evidence or theyre not.
The first principles from which the arguments proceed are the personal vendettas of a sick man. From that understanding of the first principles, the text can be read properly. From other understandings of the first principles, the text will be misinterpreted.
> the intent or state of the writer is irrevelant.
This is not true of any other political text. The intent and state of the founders is highly relevant to interpreting the declaration of independence. The intent and state of Marx is highly relevant to interpreting the communist manifesto. Even scientific revolutionary documents such as Darwin's Origins are not possible to read deeply & understand completely without learning more about the man.
The founders were nation building in a very particular context. Marx was movement building in a very particular context. Darwin was writing into a very specific scientific and political context. Reading these texts without appropriate historical and personal context would result in misreadings, or shallow readings, or, most often, shallow misreadings.
History and personal context always matter when reading texts deeply. We never ignore those things when reading other texts. Why would we suddenly start ignoring these salient details just because the author is a terrorist?