What does that have to do with anything? You've completely ignored the concept of what "per capita" even means in this context. Person B could be in Country 1 with low per capita emissions, or Person B could be in Country 2 with high per capita emissions. It doesn't change the fact that on average, individual people in Country 2 emit more CO2 emissions than people from Country 1...

Also, deciding to not do something positive because other people are still doing something negative somewhere else is a shitty argument.