Originally Posted by
Often1
2. The fact that you are gay is neither here nor there.
I beg to differ. US government officials at the pointy end of things tend to be overly interested in imposing their invariably right wing religious moral view onto the world where they can. The fact that the officer would call to confirm an identity after the interview "to flag it" suggests to me that that is exactly what happened.
4. You can appeal to the ombudsman and should make it short and sweet, namely that there is nothing in your background which ought to concern CBP one bit. And, further, if there is any detail which does concern CBP, you are ready, willing & able to clear anything up.
I would add a single sentence that the interviewer's demeanor changed upon learning the OP was gay & they followed up with a call to flag another applicants file. Don't suggest anything other than stating that. It forces CBP to back themselves up in the face of the only likely "negative" they could hang their biases on.