Totally unacceptable. Even if he believes nothing would come of the report, the way he handled it was far from professional. I've had friends file reports and LE have told them there is a low possibility that a suspect would be found, but they never dissuaded them from filing because it's good to have the report on record for the possibility that it happens again or he goes further next time he finds himself alone with a working woman.
Not only that but if it makes her feel at ease even just a little to have a report filed who is he to tell her that it's wrong? Some people just want to know the actions have been noted and are on file, even if nothing will come of it. If the mans actions made her uneasy or fearful it's LE's duty to comfort her and make sure she doesn't worry about it happening again.
With that, yes there are some creeps in the line of work but for an officer to out-right state that she needs to get used to it is unprofessional. There are so many creeps because so many people have the mindset that workers need to just accept it as a part of the job. It's sad . . .
I hope she can find a good support group and feel comfortable in her line of work again.