Economists have ethics?:

Economists are probably also more open to immigration than the typical member of the public because of their ethics -- while economists may be known for assuming self-interested behavior wherever they look, economists in their work tend not to distinguish between us and them. We look instead for policies that at least in principle make everyone better off. Policies that make us better off at the price of making them even worse off are for politicians, not economists.

Immigration makes immigrants much better off. In the normal debate this fact is not considered to be of great importance -- who cares about them? But economists tend not to count some people as worth more than others, especially not if the difference is something so random as where a person was born.

Speaking of self-interested economists, consider this:

What is in my self-interest? Providing arguments and evidence about the truth. People read this blog and buy my books because they find the discussion of economic issues cogent or at least thought-provoking. My self-interest and relentless pursuit of the truth are not conflicting goals; they are two sides of the same coin.

Or maybe it's just in my interest to have you believe that.