it is disrespectful to say to the client "you are seeing this wrongly because you have ptsd" because it essentially means "you are crazy that's why you are seeing stuff that isn't there" or, at least, that's how it feels to the client. It only re-enforces the idea that something is wrong with them, which is one of the main causes of their suffering in the first place.

A much better way for the therapist to address the event in question, as I said, would've been to give her own opinion about it and to explain what it is based on instead of making it about you.