You're not actually addressing the accounting question though. The argument isn't about the economic benefits or consequences of manufacturing, it's simply about where we assign the carbon emissions in an accounting system.

Whether Chinese workers benefit economically from manufacturing exports doesn't change the fact that when a US consumer buys a product made in China, we could reasonably count those manufacturing emissions as US consumption-based emissions rather than Chinese production-based emissions.

This is really a question of "but for" causation: but for US consumer demand for these products, would these specific manufacturing emissions have occurred? If the answer is no, then there's a strong case for counting them as US emissions regardless of where the factory happens to be located.

Your point about global emissions sidesteps the question entirely. Of course all emissions are ultimately global in their climate impact, but for policy and measurement purposes we still need accounting frameworks. The question is whether production-based or consumption-based accounting gives us a more accurate picture for policy decisions.

The unemployment and poverty argument, while valid for other discussions, doesn't really bear on which accounting method better reflects responsibility for emissions.