Funny, I read that same section two weeks ago. Dawkins’ definition is not what geneticists typical consider a gene. His “gene” is more like what I would call a haplotype in that he divorces “gene” from “protein-coding” region. But he has a good point and I like this section. But he wrote it in the genetic dark ages and we now know quite precisely where and how often recombinations occurs, and for how long haplotypes are preserved as a function of generation numbers.

Highly recommend David Reich’s book for are good overview of the math of recombination in humans.

https://www.amazon.com/Who-Are-How-Got-Here/dp/1101873469