Pamela,
You are asking why curators are allowed to curate their own family. There is a two-part answer.
First, because a non-family member wouldn't want to take the time. When I make an MP I am making a commitment to the Geni community that I will participate in resolving any problems and stabilizing the data ("curating").
For most profiles that commitment is negligible, but in the event of a dispute it can be huge. It would be non-sensical to expect someone to take on that kind of responsibility in area where they know nothing and have no interest.
The best curator in a given area will be someone who has already researched the area and knows the problems, or at least someone familiar with the cultural, religious, and economic history who is willing to put in some research time.
It wouldn't make much sense to say, "Hmmm, Justin is a medievalist. Let's make him do 18th and 19th century Italian politicians."
As a corollary to that, it would be very difficult to find someone with a strong skill set, interested in English gentry, who is not related to them. These popular and contentious profiles are popular and contentious because so many people are descended from them. If you disqualify every curator with a Warren connection from working on the Warrens, you'll disqualify everyone with an interest in gentry families.
To be continued ...