It's a clever idea, but how long before border authorities simply order travelers to log on to 1Password and turn off travel mode, or be denied entry? I'm guessing not very.
Is plausible deniability the right term here? Usually that's about the ability to deny having known about or authorised something after it's already been discovered.
I'm not really sure how you'd refer to the concept "they don't know I have it, so they don't know to ask". Security through ignorance?
My thought on this whole situation is to simply not take my phone or laptop. I don't live nor work in the US, however, so I don't have the issues being faced by people in this thread.
What we really need is plausible deniability - if they don't know you use 1password, they don't know to ask for it.