word choice - What is the proper way to refer to the Original Poster (OP)?

In a comment, I was corrected by referring to a user named alice as a "he". I said (context):

I know he thinks he needs all of the eigenvalues, but I've learned that ...

and was corrected to by another user

But a protip: the username "alice" and the pronoun "he" typically don't go together. Probably better to stick to gender-neutral singular they.

Which of these would be correct?

1. I know he thinks he needs all of the eigenvalues, ...


2. I know he/she thinks he/she needs all of the eigenvalues, ...


3. I know they think they need all of the eigenvalues, ...


4. I know the OP thinks they need all of the eigenvalues, ...

Clearly this question is related:

Is there a correct gender-neutral singular pronoun ("his" vs. "her" vs. "their")?

I'm interested in the last case where OP is essentially a pronoun, but the usage sounds awkward. Is there a good way to refer to OP or should I stick with "they"?

Answer

As the comments say OP is a noun here.

He/she is too longwinded. "They" is gender neutral. Theirs, they're, they are, them etc.

I would go with option 4 as it identifies "them" as "the OP". Option 3 could confuse readers about who the actual subject is.