Sounds like an 'opportunist' TWOC, not specifically targeted to either the car or yourself.
Imagine a scenario where you had a highly desirable/valuable motor & that guy had a shipping container leaving for Nth Africa next week, I'm told that £500'ish is the going rate for anything presented to the main gangs shipping them out. Imagine if that car can ONLY be started with the key.
Here is the car & you have the key. He wants/needs that key, you can either hand it over politely or what do you think might happen?
My business partner in the recovery treated himself to a very nice Audi RS, a few weeks later 2x guys bomb burst into his bedroom at 2am because he hadn't left the keys within 5 paces of his back door.
He currently drives an 04 Disco.
First off, I'd never buy a top of the range car, even if I was a lottery winner.
Second, if I was 'threatened' for my car keys they would get them no problem.
No vehicle on earth is worth more than my, or any member of my familys, life or well being.