I think this is just due to a misunderstanding of how genetic traits and risks work. Insurance companies may be angling for the government to be the insurer of last resort for the most costly genotypes.

If there is anything that it makes sense to utilize a risk pool for, it is the random chance associated with heredity. Aside from a small number of well known, highly hereditary genetically-linked conditions, most people just reproduce without thinking much about the probability that their offspring will end up with an unlucky genotype. This is mainly because there is so much chance involved and a low probability of the child getting a "costly" genome, at least the cost impact of drawing a 99% probability genome is far less than the impact of an additional year of maternal age, etc. Even for the most strongly hereditary diseases, random chance still dominates the impact of heredity on the chance of the offspring getting the disease.

Also, evolution ensures that most "harmful" genes are also helpful in some way... so while there is likely an expected dollar cost of a given allele, I don't think there's enough variation in overall dollar cost to make it worth the hassle for anyone (including insurers), which points again to the notion that they are simply looking for corporate welfare.

For comparison, post 9/11 the insurance industry extracted a big handout when the US Government became the insurer of last resort for terrorism related claims > $1B. My take is that genomes that are highly likely to cost more than a standard deviation greater than average are rare enough that it wouldn't even make sense from a competitive perspective for insurance companies to try to evade issuing policies to such people.