Is it rage? Is it despair? To what extent does it matter for the purposes of profiling? Or for discussing the wider social or moral context of his crime?
I think it's all just a continuation of a modern dialogue about grievance and protest and what are and are not acceptable methods for communicating and addressing one's grievances. Over the summer there was a similar argument about damage and unrest in many places. You had people saying peaceful protest is fine but that we should draw a line at protests that involved looting, smashing windows, starting fires, damaging homes and businesses. There was a rebuttal to that, more common in some political circles than others that "it's just property" and that it was callous to bring up property damage to people who are acting in response to concerns about government actions and policies they felt meant people's lives being actually in danger.
We can't know whether or not AQW was even paying attention to any of these arguments, let alone if he was swayed by any of them. It may be that he saw his own death more as a sort of martyrdom than any of that. In that way maybe his mindset was more similar to the Tunisian street vendor whose act of self-immolation is often cited as a galvanizing event in the Tunisian protests that set off the Arab Spring.
Is it rage? Is it despair? Or is it a type of narcissism, a delusion of grandeur, a way that somebody who feels insignificant and victimized constructs a new self-narrative where they can play the part of the brave revolutionary instead? Or even where they, wittingly or not, become the victimizer? I think there's an argument for all of the above, that often despair that leads to self-harm is kind of an internalized rage, and this act had both that component, and also externalized rage.
Someone like Timothy McVeigh is all externalized rage. He wanted to cause significant damage. He didn't want to die for his 'cause' but he was unconcerned if others did. Meanwhile the vendor who set himself on fire wasn't trying to injure anyone or anything else, that was all internalized. IRA car bombers apparently used to give warnings to minimize casualties. But they typically didn't blow themselves up. The Boston bombers were trying to maximize casualties, but they weren't suicidal.
So this bomber doesn't fit neatly into boxes we'd like to stick him in. We don't share his grievances, we don't approve of his methods or their results. There is much about him not to like.
But I think in the middle of a pandemic and the intense social isolation it has caused there's something that hits a little too close to home for some about his loss and his loneliness too.