Part of the appeal to Geo Engineering comes from hopelessness with the politics. In a way that marries perfectly with the denier narrative. The Koch Brother types want you either to deny or to give up hope. Both serve the same end.One of the things I emphasize in my own critique is the nonsensicality of this particular argumentative move. Every geo-engineering mega-engineering wet-dream, were it to move from fancy to actual implementation, would require the very politics (funding, regulation, dispute-adjudication, maintenance) to work relatively effectively the specific denial of which tends to be the enabling condition for entertaining these boondoggles in the first place. As often happens in futurological discourse, we are never more than a hop, skip, and jump away from straightforward magical thinking here.
I agree with you that "geo-engineering" plays into denialism. In my earliest critiques of "geo-engineering" I actually declared its anti-politics a kind of second stage climate-change denialism: where many begin by denying the scientific consensus about catastrophic anthropogenic climate change "geo-engineering" enthusiasts end by denying the possibility of any democratically accountable equitable collective response to the shared problem of catastrophic anthropogenic climate change. Chris Mooney in particular pooh-poohed this point of mine as a real stretch. But it seems to me a fine way of understanding what Al Gore has famously diagnosed as the tendency of so many folks to leap from a kind of denial to a kind of despair that keeps them maddeningly passive in the face of climate catastrophes like pollution and resource descent.