How can one calculate "probability of possessing a ‘perfect’ profile" from "typical optimal genotype frequencies"?
They appear to have simply considered each allele independently. This means that if there are say 2 alleles for a trait, and they are both present at a frequency of 0.1 in the population, then you have a 0.01 chance of having both of them. This is probably an okay assumption for their purposes (in reality some might be linked and would associate non independently). Their point is simply that as the number of alleles go up, having all the best ones becomes increasingly unlikely.