The issue is that his alleged "father," Barack Obama, Sr. was not a US citizen, which means that Ann Dunham's son Steve is not a natural born citizen, which means he is ineligible.
If you re-read the dicta, the 9th Circus says that a foreign-born baby needs only to be biologically-related to a US citizen (only one US citizen needed as is clear in the case) to be a natural born citizen at birth.
The Obama legal team takes the additional step of claiming that statutory citizenship at birth of any kind, as defined in the State Dept. regs. equates to NBC POTUS eligibility...a leap that the State Dept. said had not been ruled on by SCOTUS as recently as last year.
"Steve"?
Why is that so difficult for so many folks to understand?