The word "easily" is doing some work here, as your scenario is already in the area of "rubber-hose cryptanalysis", where passcodes don't stay private for long either.
Fair enough. The threat model I have in mind here is cops and customs agents violating one's (US) fourth amendment rights. With FaceID they don't need your passcode to unlock your phone. With a passcode, they cannot legally arrest you [yet] for refusing to provide it.
while they are restraining you, how are they preventing you from keeping your eyes closed?
I actually wonder if it’s possible to coerce someone to use Face ID. If you have it set properly it requires your eyes to be open and looking at the phone, so someone can’t use it while you’re sleeping. They would have to hold your eyes up at that point Their hand is in front of your face. And how can someone force you to look in the right direction?
By telling you that you'll spend the next 10 years at CECOT in Honduras if you don't look in the right direction.
I thought it was common knowledge that for privacy and security you should have FaceID (and before that, fingerprint reader) disabled in favour of a password.