That matches my understanding too. Unfortunately it sounds like the poster was suggesting to wipe the device after the government requests access, and was probably not planning on telling the officers about the trigger.
There are videos on youtube where the lawyers tell you what your rights are at traffic stops, also there are ones that talk about the different rules when coming through immigration. These can be painful to see when they show the ones where cops ignore limits.
So at the border, they tell you that you are legally required to provide your finger print, you do that, and don't say a word. I'm sure it will be a bad day for you, regardless of how it works out after years of litigation on whether it is your duty to tell them how NOT to unlock your device.