Use 'this' or 'that' to refer to the original post in a comment

Question

When I'm leaving a comment to a post and I want to refer to the post, should I say 'this post' or 'that post'?

It feels natural to me to say 'this post', however, my English teacher told me 'this' only refers to something in the upcoming text. 'That' should be used when referring to something that's said earlier.

Is my language sense wrong, my English teacher was wrong, or the situation (leaving a comment on a post) is different from what she was talking about (writing a complete piece of text)?

Answer 1

In this case, as I comment on "this" post I use the term "this" since it describes the current post we are working on and not another post.

"That" would refer to another post, which would have to be referenced within the context of the sentence.