"the fossil record is incomplete, but even mainstream evolutionists have asked, why is it selectively incomplete"
Really? He said it was "selectively incomplete" -- which implies a conspiracy (the selectors). Obviously unless you uncover the bones of every creature that ever lived, you could say the fossil record is incomplete. But when you alledge it is "selectively incomplete" you are imputing intentional hiding of fossil evidence that would contradict whatever the conspirators don't want to see the light of day.
So again, I'm wondering which mainstream scientists have alleged "selectively incomplete" fossil evidence. Do you have a citation from Gould where he makes this conspiracy charge?