This is an important argument to consider, but I think it is not so obvious that this is true. A hidden assumption in your calculation is that poor people emit

This is an important argument to consider, but I think it is not so obvious that this is true. A hidden assumption in your calculation is that poor people emit the same amount of CO2 as rich people. Poor people may not have a car, and may not take a plane to go on vacation. They are also likely to live in a smaller apartment, reducing the heating/AC costs. This is probably more true if you view this on a global level. Even if CO2 taxes are regressive, you could think of a way to compensate for this by altering tax rates/brackets