The legal test is: what is the reaction a "reasonable" person would have to same situation. It is not: what is the reaction a person with post traumatic stress syndrom would have. For instance, flashbacks are often triggered by scent of shampoo or cologne that abuser wore. Should woman be able to sue manager of restaurant if she smells same cologne he is wearing or they use same soap in bathroom as her abuser used and she has flashback? Of course not, it is not reaction a reasonable person would have. It is reaction of person with psychiatric illness. Is society expected to alter realty and entire world to sensitivites of few mentally ill? It is impossible and unreasonable.
You're talking about the "reasonable man" test. However, there is more than one way to apply it. For one, you can apply it a "what would a reaonable person do in the plaintiff's position," which is what you are doing here. However, you can also apply it as "what would a reasonable peron with the plaintiff's condition do?" This is the standard used in personal injury.