It sounds like the logical conclusion of this is that police should go door-to-door searching everywhere in case they might discover more unabombers.

I don't think this is a good idea, as in the whole history of the world only one of these lunatics has turned out to be the unabomber.

This, BTW, was not even how Kaczynski was found. Which is why I find it rather odd that you'd bring him up.