I think you may have read the line here out of context: previous posts acknowledge areas where the author needs God’s help and has fallen short in hurting others, for example, so there clearly isn’t any intention here to undermine those previous posts.
This post is specifically about suffering from an eating disorder and being judged for it, by appearances. The statement ‘there is no sinner’ following this explanation seems general but is directly related to the above situation: so unless suffering from an eating disorder is a sin or inherently sinful in and of itself, she is not a sinner in this, and there is no sin to forgive or judge.
My best friend also suffered from an eating disorder that she eventually overcame through years of struggle. If anyone looked at her and said “ah well, love the sinner, hate the sin” I would have done something very UnChristian, because I’m human, and a sinner, and that would have outraged me. The only sin there would have been mine. Not hers.
I can see the one line read out of context jars with the rest of the post which explains its framework.
It is from the heart and so not meant to be a tight argument; it’s not by HuffPost or The Guardian or the Western Mail, it’s just a post by a lady trying to get all her stuff done day by day and keep up with the Advent series she wants to write. She isn’t trying to piss you off (except to challenge your perception of people struggling with their weight and disordered eating) or demonstrate ignorance of Scripture.
She’s writing about one facet of her life, not all of it. And in that one thing [struggle with disordered eating] there is no sinner, no sin, only you and her.