In regards to Jason Richwine's Harvard dissertation that discriminates different racial groups in immigration policy, what he said about races with lower average IQ pulling down the average IQ of Americans is actually true.
First of all, the minority few of the other racial groups who are the exception that have high IQ and well-educated would most probably make it in their home country, and would not require to migrate so far to the United States for greater opportunities to earn a better living or even just to live a more abundant wealthy life.
The United States is one of the cheapest and easiest countries in the world for lower skilled immigrants to migrate to. Without the US having proper immigration safeguards, the lowest skilled immigrants from all over the world can easily make their way there.
The majority of those who would have to migrate to the US would be those who would seek lower-skilled jobs, and would compete with the lower-skilled lower social classes of American citizens for jobs. This would lead to greater job competition among them, leading to the lower-social classes of US citizens to become poorer in the end.
Allowing in such immigrants is to take in the social-economic problems of other countries and adding it all together in the United States. If the US handles all the 'economic rejects' coming from other countries, it is the lower-classes of US citizens who will pay the biggest price.
Because the US is one of the most heavily targeted countries for the lower skilled immigrants from all over the world, it has to implement very strict immigration safeguards to protect the livelihood of the lower-classes of Americans.
People who oppose the rule such as politicians, TV personalities, writers, students, journalists etc are often the ones who are financially well-cushioned or have already made it in society so they would not feel the pinch and would not understand the social-economics problems that would surface for the lower social classes of American citizens. They should first consider the well-being of the lower social classes of Americans before worrying about the well-being of immigrants. They want to protect racial equality at the cost of causing the poor in America to become poorer, which will only widen the social income gap.
However, if the US takes in high IQ immigrants that are not social-economic 'rejects', then it is the upper social classes of US citizens who would face the competition from such high IQ immigrants. But it is more bearable for them compared to poor lower-classes US citizens facing such job competition.
But for an immigration policy made for the US, the ones to reject would be the main focal point of such a policy rather than to consider the ones to take in. An immigration policy should not worry about the exceptional few with high IQ. For the exceptional individuals from such a group who has high IQ, they could survive elsewhere without needing to immigrate to the US, so people should not worry too much about them. (I don't think the US is the only country in the world, and why would truly smart people want to go live there anyway? lol)
So for the well-being of the lower social classes of US citizens, the immigrants to be mainly rejected should come from the group who would pose the greatest competition for the lower social classes of US citizens. And the identity of such a group is already well-defined.
The bottom line is that the US has to worry first about the well-being of its own lower-class citizens. It is currently in no healthy economic state to perform charity by catering to any exceptional few(and overlook the rest). If it wants to perform 'social-economic charity' at the sake of being 'politically-correct' and 'fair' then it is the lower classes that will suffer the most.
The American dream is already dead, now is the time for the US to reduce its losses.