Well, it's fairly easy to turn off. If you are in a situation in which you think you might be stalked through technology, you should certainly check your Find My along with any applicable location sharing Applications (both Android and Apple, such as google maps location sharing).

So I doubt this will be used much as a stalker feature. Unless of course they hide a phone on your person/vehicle in such a way that it is both totally unnoticeable to you AND maintains a very clear view of the sky. Apple said that sending messages could take a minute or more with even light foliage, so hiding it in/under a car will be a total no-go.

You have control over who can see your location in Find My. If a stalker has access, that means they're already someone you trust or you've never looked at the list of people you're sharing your location with.