It reads to me as a record of a very intelligent person having a total mental breakdown (likely as a result of being drugged and tortured by the CIA as part of MKULTRA). It contains some cogent points about capitalist alienation resulting from the industrial revolution (without identifying it as such), but is also full of homophobic, reactionary, and ecofascist rhetoric. It also completely falls flat with the conclusion being that the only way forward is a complete rejection of technology and modernity, without presenting a compelling alternative.

You should read it. It's short, and easily available. I read it just before the Covid lockdown, and I'm so thankful.

He later walked back his response (blowing people up) and advocated for people to heavily educate themselves on technology so they could guide it and combat it.

That said, it's hard to disagree with most things he wrote in his manifesto.

Half of it is just him whining about leftists ruining everything

Yeah he makes some solid points, it's worth a read. The bomb stuff was just a ploy to get it published, it's not like reading it is going to turn you into a bomber.