"doesn't need to do anything" is a qualifier that _you_ added, apparently based on a gross misunderstanding of the conversation. We're talking about defining an ideal target here, with deference paid to the fact that the status quo poses some inertia. If we're talking about an idealized frictionless vacuum, everybody would snap to the same emissions per capita, at the level required to forestall the negative effects of climate change. This would imply a substantial reduction of US emissions and perhaps an increase or small decrease in Indo-China emissions; increasing China to US levels doesn't make sense in any model, idealized or otherwise. Given that inertia means that the US reduction can't be immediate and drastic, it still suggests that mroe of the burden for emission reduction falls on the US than on India and China.
No it doesn't following GP's chain of logic. It doesn't need to do anything till the point it hits US per capita.