These type of broad questions are a good conversation starter.
How the person goes about leveling their answer is very telling. Is it collaborative with the interviewer to figure out what level of detail is appropriate? Do they immediately interpret the question one of several ways and shoot off an answer? When asked to go into more detail, are they annoyed, happy go give in depth technical explanations, talk about where they would go for answers?
It may not be worth the complexity to give users the choice. If I were to issue keys to guests this way I would want my revocations to be immediately effective no matter what. Guest keys requiring a working network is a fine trade-off.
You can have this without user intervention - have the lock download an expiration time with the list of allowed guest keys, or have the guest keys public-key signed with metadata like expiration time.
If the cloud is down, revocations aren't going to happen instantly anyway. (Although you might be able to hack up a local WiFi or Bluetooth fallback.)
How the person goes about leveling their answer is very telling. Is it collaborative with the interviewer to figure out what level of detail is appropriate? Do they immediately interpret the question one of several ways and shoot off an answer? When asked to go into more detail, are they annoyed, happy go give in depth technical explanations, talk about where they would go for answers?