I already said my piece on Muir upthread, but I want to make a few more points.
I would expect an African to be able to be the fastest clean runner. What we know about genetic and cultural advantage of the population is true (emphasis on "population"). On the other hand, it is much more complicated when you begin discussing social advantages of western athletes, and you redifine the population along those that can realistically have athletic ambitions. I don't expect a western male athlete to hold the clean WR. But for now, it seems more possible for western born women.
Second, the "is she clean or doping" question is not useful. We can see that the question is not helpful for the discussion and leaves very little in terms of thenstrength of someone's supicion.
I propose the 1-10 scale for suspicion. To calibrate, Dibaba is a 10 for me, given allegations against coach, teammates' doping bans, doping/anti-doping culture of Ethiopia and top level athletics, and her performance level in that context.
Muir was a 3, maybe a 4 after 2015. Everyone I don't "have anything" on is a 3. Her coach has no bad associations, no bad teammates, her performances hadn't been crazy, and nothing showing an anti-doping spirit either in rhetoric or practice, such as releasing blood scores (like a Robert Harting or Arne Gabius, who are a 2 or 3)
Muir is going faster now, but the IAAF tables are one tool tonshow its not that fast. Another is that Dibaba is 5(!) seconds faster. I'd put Muir at a 5, where I have Simpson, Rowburry, and most other top caliber athletes: the only thing "against" them is that they run fast and perform on the level or above the level of known dopers (Rowburry has bad coach associations etc. , but I don't think it is a team wide program).
(And to explain because people couldn't understand it in the other thread, 5 does not mean I am convinced they are doping. Don't reply saying I think everyone dopes. That's the reason for the scale: 5 is far from 10. But I'm certainly open to the possibilty she could be doping.)