The pre shoot meeting is imperative!
I always tell my boudoir clients that I try to have at least a female assistant at the shoot or my wife. I get a feel for what the client wants before hand and set any expectations. I allow escorts as long as they don't get in the way or try to dictate to me. I've never had an issue to date. If I get a 'feeling' that something is not right, well that time just got booked and all other times are booked also.
Her not wanting to see your previous work is a red flag though. How does she know you are the right photographer for the style she wants? Her saying that the escort will be a cop, doesn't bother me. Heck, I'm a former cop and I'd be able to talk shop and know if that person is truly who they say they are.
Take the preshoot meeting, preferably in a very public place, and interview her like you were going to hire her. Totally understand what she wants and set her expectations. Bring your portfolio and show her what you shoot. Make sure you are both comfortable and make your decisions accordingly.
She may truly be nervous, the last lady I shot boudoir with was also nervous, but she said that because I had a female assistant, and that assistant had modeled for me before, that she was very comfortable.
In our preshoot discussions, she wasn't going to do any more than the lingere, but after meeting my assistant, seeing how I shoot, and witnessing my professional manner with her, she got comfortable with me, it all came off. She, and her husband, have some fantastic images. He even bought digital images for his laptop!
So are there some flags? Yes, it's up to you to determine if they are just hoops to jump through or true obstacles to the shoot.