Sure, if he's saying he is powerless against higher powers. But if he's trying to make a quantitative assertion, a qualitative analogy is not the right tool.
>The purpose of an analogy is to simplify something that's too hard to understand for the person you try to convey your idea to
An analogy applies a principle to a common setting without loss of specificity. Specifically the dedicated adversary is lost in this abstraction, so it's a bad analogy.
Not only do you likely need to populate your host with packages not from your host. But also, your host will also still be connect to a public net, even if only indirectly (e.g. private net), and hence potentially manipulated.
> If a business card can delight people who receive it, then it has a point.
The first rule of the advertising club is AIDA: Attention, Interest, Desire, Action. A business card should draw attention, if only to distract from the terribly clichéd action of handing over a business card :)