So, if they're already in the business of demanding your passwords (otherwise this whole thing is irrelevant), why don't they just ask you to log into your 1Password account and see if you're in travel mode there?
It doesn't really matter. If you're an American citizen, you can just refuse and they have to let you enter. They might confiscate your device, but they can't turn you away from the border.
And if you're not a US citizen, "I'm not physically able to unlock the account right now" doesn't buy you anything. There's no obligation that says if you do all you can physically do to accommodate their wishes, that you get to enter. If they want access, you either grant access or you get back on a plane. The only thing not having your 1Password credentials with you does is remove the choice of which you want to do.