It already does. Biometrics of any kind are not protected if the police have a warrant which is what happened in the story you linked.
It is not as black-and-white as you make it out to be (which was my point -- this will likely end up in the Supreme Court at some point). Specifically, some courts disagree with your position, and hold that even with a warrant, you have a fifth-amendment right not to incriminate yourself.
See for instance https://www.forbes.com/sites/thomasbrewster/2019/01/14/feds-...
> But in a more significant part of the ruling, Judge Westmore declared that the government did not have the right, even with a warrant, to force suspects to incriminate themselves by unlocking their devices with their biological features.
The issue is, of course, in the meantime, it's far easier for law enforcement to execute a fait accompli and get a suspect to look at their phone to unlock it.
1) Triggering the fingerprint sensor requires an active action, 'touch this sensor', versus Face ID (even with attention-detection enabled). This is important for law-enforcement. It is easier for law enforcement to get you to look at something that it is to compel you to unlock something.
See for instance https://www.wired.com/story/police-unlock-iphone-face-id-leg... Note that some courts have ruled that Face ID should have similar protections as Touch ID, but the issue is far from settled and is likely to end up in court in the future.
2) It's easier in mass-transit and POS scenarios to tap your phone while touching the fingerprint sensor. The flow for Face ID is much more convoluted -- bring the phone near the reader (which may be away from your face) to bring up the payment UI, then bring your phone to your face if the reader is faced away, double-click the home button...
3) During meetings, it's easy to sneak a glance at notifications (if your notifications are set to show only when authenticated) by touching your fingerprint sensor -- there's no need to bring your phone to your face and make it obvious you're checking your phone.
I don't mind Face ID, to be clear. But I always felt Touch ID was more unobtrusive.