^Yes, but the point is that Marla claimed to recognize Khan as a Sikh on sight
, knowing absolutely nothing about the man but what he looked like. And since there was nothing about his appearance that suggested that he followed the Sikh religion, this was impossible.
The only way to rationalize it is to assume that Marla recognized Khan on sight and lied about it. That's the only way she could possibly have known that he was a Sikh.