After #833, we are left with the following possibilities:

1. Bob is authorized; he can retrieve for the first time.
2. Bob is authorized; he can retrieve using cached CFrags or through the network (though he gets TypeError if he tries to use the network with a Capsule that is already activated)
3. Bob is unauthorized; he cannot retrieve using the network.
4. Bob is unauthorized, but he has cached CFrags (in fact, an activated Capsule).

What do we do (or perhaps do about) number 4 here?

Some possibilities:

A) We always delete a Capsule after Bob has obtained The Secret (ie, no caching is allowed, ever)
B) We leave well-enough alone; Bob can do the wrong thing unless dapp developers affirmatively prohibit it.
C) We provide an option to do (A) at the developer's discretion.
D) ...?