Doesn't that only support their point? A naively optimistic estimate that ancestors are uniformly distributed will take more generations to hit the limit of 2^n

Doesn't that only support their point? A naively optimistic estimate that ancestors are uniformly distributed will take more generations to hit the limit of 2^n vs the historic population. In reality ancestors are "reused" even faster than that, particularly with examples like geographically isolated villages, etc.