David B. has written the second part of his criticism of Frank Salter. Some comments of my own on the first part here. And some numbered comments on the second part here:
1. I see this as a minor point and one that can ultimately be defeated by either the "correlated alleles" approach or the "how small a difference is too small" approach.
2. Well, only in the case of polymorphic genes does it make sense to speak of competition between alleles, so I'm not sure I understand this criticism.
3. I agree with Salter on this one. Adaptive to an environment X = increasing in frequency when found in X. If an allele for a disease finds itself in an environment which favors it, even if it's an "irrational" environment which wants to perpetuate the disease, the allele is still adaptive.
4. I agree with David B. here. The human genome has mutations which are either neutral, adaptive or maladaptive. From an evolutionary perspective, an ethnic group ought to value adaptive mutations, because these are its strength. From a psychological perspective, an ethnic group might value its distinctive mutations even if they are neutral and maladaptive, e.g., mutations for a particular distinctive physical trait, e.g., the convex nose which was highly valued by Ancient Persians (*), or the freckled skin of many NW Europeans (**)
5. Related to the previous point. It is certainly the case that from an evolutionary perspective maladaptive alleles should not be preserved. For something like sickle-cell disease, an ethnic group removed from the malarial environment would probably feel no attachment for the trait, but this may not be the case for other traits mentioned in #4.
In conclusion, Frank Salter's work is one extreme in the spectrum of ideas, proposing the "objective" value of the ethnic preservationist strategy. At the other end is the older ideas of the more "tolerant" representatives of Nazi Rassenkunde, who did not ephasize the value of the Nordic race on the basis of its superiority, but rather of its distinctiveness. Richard McCulloch is the most prolific modern representative of this school of thought.
We could in fact break down ethnic preservationists based on whether they approach the issue of ethnic preservation on the basis of the distinctiveness or the superiority of their own ethnic group. Traditional racism maintains both distinctiveness and superiority. Eugenically-oriented preservationists emphasize the "deterioration" that would result by admixture rather than the loss of distinctiveness. Someone of McCulloch's ideology emphasizes ethnic distinctiveness and the need for preservation of distinct human forms, much as we seek to preserve endangered species. And, finally those who are neither interested in genetic distinctiveness nor in genetic superiority can be termed as cultural preservationists, emphasizing the non-genetic aspects of ethnicity. This ideology is dominant, or at least traditional in many modern nations (e.g., France) although it is increasingly challenged by the adherents of multi-culturalism who generally maintain that neither the genetic nor the cultural aspect of an ethnic group needs be preserved, but rather that countries should evolve in the direction of co-existence of racial stocks and cultures within the state.
(*) The convex nose may have had an adaptive origin in the distant past, but was hardly in more recent historical years.
(**) Freckled skin is associated with various skin diseases. It too might have had an adaptive, or at least neutral origin in the distant past, but not today.