boom, that's what I was getting at with your action of letting someone know in the presence of the other person that your current location was your last known whereabouts.
Was what happened to this woman a horror? Absolutely.
Do I believe that every meet up with someone from craigslist may meet with a murder? Absolutely not.
However, when one is meeting a complete stranger, you need to be aware that any number of things could go wrong. That would include robbery, assault, or any number of things that could make you feel the situation is not on the up and up.
Is it paranoid to walk into a situation with a clear plan of what you would do if something did go awry? Absolutley not. This is not a black (I'm going to be murdered) or white (everybody is just so nice) situation. It's using the prudent caution of an intelligent person to avoid any type of mishap.
Perhaps this woman would not have been cut open, and her fetus killed if when the crazy woman answered the door, she let her know that someone was waiting for her in the car (and pointing to that person) or making a call as you do letting someone know where you are.
If someone did that if they were coming to my house (and I wouldn't do that, I'd meet in a neutral place) I'd think that they were pretty smart and careful.