This is the sophisticated version of the 'do nothing' argument. It's not a good argument in any form. If the greenland ice mass melts billions of people who live on the edge of the sea are at risk. If rising ocean temperatures continue to degrade coral reefs, a big part of the world's food supply is at risk. how does bringing people out of poverty offset that?
> how does bringing people out of poverty offset that?
By giving them the ability to adapt. Most of The Netherlands is below sea level, and has been for centuries. They responded by adapting: building dikes and levees and other systems for water management. They could do this because they had enough wealth to do so. The more wealth we create, the more the world as a whole has the ability to adapt.
If we knew for certain that putting all that wealth into CO2 mitigation instead of bringing people out of poverty would keep things static indefinitely, it might perhaps be worth considering mitigation (though you will note that nobody who advocates mitigation asks all the poor people what they would prefer). But we don't know that, not even close. We have to assume that things will change no matter what we do. Given that, our only realistic option is adaptation.