They may have a point, that won't change the reality of the situation: letting them do exactly what the developed countries did, will kill them. That's not fair, that's life.
> So yes, idealism likely will not solve anything. But it can help make the transition to a sustainable economy.
No, idealism by definition will produce idealistic solutions that won't amount to anything. You are advocating for controlling a system by considering that with enough ingenuity, trust or whatever, we can do it. No, controlling a complex system is done by understanding its baseline or attractors and tweaking its inputs carefully to bring it and maintaining it there.
It means indeed that injecting aerosols in the atmosphere to control the climate is a foolish errand, and the practical approach is energy sobriety. But don't go advocating this position by talking of ideals and fairness, you won't convince anyone.