This is a complicated situation, but in my opinion, probably the correct decision.
Given this is the ruling, if you do believe your phone is about to be confiscated, and you don't want its contents to be used as evidence, it might be a good idea to turn off your phone. Although the police cannot compel a password, a biometric unlock is not a password. If you turn off your phone, it will generally require a password to enable biometric unlock.
It is complicated in the US because of biometrics and the wide use of contempt citations. If you “forget” your password, you can be held in contempt and jailed for up to 18 months (I missed that; last I knew it was indefinite). Biometrics and other “something you are” items can be forcibly taken (eg your fingerprints or retinal scans) with full legal backing. Your perspective, while laudable, only exists in the potential future orgs like the EFF and ACLU are fighting to create. It is very wrong today.
Or squeeze volume up button and power button. Encrypts your data and requires passcode unlock. Also, set a long passcode like 10 digits. 4 can be cracked in minutes. 6 can be cracked in a few hours.