It isn't about you individually, it's about big numbers, statistics. It's just an additional tool in their arsenal. Similar to why doctors perform standard exams even when you come in and complain about something where that particular exam seems ridiculously wrong. The procedures are not invented new each time for every person, they are based on what works "statistically". On that level they found that in (some low) x percent of cases having such a signature helps, so they include that question. And occasionally they even catch someone gullible to, or who can't manage their emotions, but that's just an additional bonus and not even the main reason for the question(s).
Do border security understand how password managers work, or would I have to tell them how to access my own data?
Showerthought: If I delete my password manager from my phone, maybe the password manager should perform geolocation and detect if the application is trying to be installed at an airport (possibly indicating installation against my will). That's a very nuanced situation.
[0]: https://www.schneier.com/blog/archives/2009/10/evil_maid_att...
1. Lying to them falls under "fraudulent access to the USA" and the penalty is permanent exclusion, no Visa will help you, you have no right to appeal.
2. You cannot discuss or appeal anything, there isn't a discussion that you are a part of in which you get to explain your side or proffer an excuse... your actions already did your talking.
Don't lie to border control, don't give BS excuses. Either you're willing to give them access or you shouldn't have boarded the plane. "I can't because I don't remember" is not a right to enter the USA... you do not have that right, the right is granted by them.
*excluding US citizens, who are also affected by these practices.