One of the major flaws in Jeanson’s model that I immediately see is the conflation of heterozygosity and genetic variation. Those are not the same thing. Almost everyone is heterozygous for DRB alleles, but that doesn’t mean there are only 2 DRB alleles. In fact, there are thousands of different DRB alleles for each DRB gene. There is simply no way that a small group of humans could contain thousands of alleles for a single gene since each person only carries 2 alleles.
From what I can see, if we grant that each kind was established by 7 pairs then there is a max of 14 alleles between them for each gene. If we looked across a proposed created kind, do you think this would hold up? If we did sequenced 1,000 genomes from each species within a kind, would we find 14 or fewer variants for each gene? I highly doubt it.
Edit: I should have said HLA alleles instead of DRB. You can check out the stats on human HLA alleles here: