Greg Cox wrote:
At the time, I wrote the books there was no reason to believe that Marla was mistaken, but it was also obvious that Khan was not a traditional Sikh. So I wrote him as someone who had Sikh roots, but, as a superior being, did not consider himself bound by any merely human traditions or beliefs.
Was it Space Seed
or Tomorrow Is Yesterday
where Spock said that the records from the 1990's/2000's era were "fragmentary"? In this case it might indicate that the divergence of the universes occurred centuries before Enterprise, since the Roddenberry Universe might not have that piece in their computers, while the Abrams universe has that piece. Or it could simply be that that fact was only available in hard copy books that Admiral Marcus had access to on Earth, but was not available in digital form for the Enterprise to access in the Roddenberry universe.