I have seen this "trend" before but this was the first good photo I could find depicting it. I don't know where/who started this, but many hipster girls are doing this "let-me-try-my-clothes-backwards" thing. So yes this post is legit and not just a one person thing.
My only concern for this look/trend is whats going to happen in the front. A cardigan would be all bunched up at the knock if it's worn backwards.