It has every single thing to do with the bearing of this conversation.
If the police tried to use biometrics to search my device today they would find exactly nothing.
On the average person's phone they likely wouldn't find much that's actionable in a legal sense.
The average person has a threat profile where it's much more likely that they would worry about a snooping parent, sibling, or significant other, or even coworkers over the police.
That is who biometrics are for.
For anyone else who has a threat profile that should require them to be worried about police intervention or investigation of any kind, there's either a burner phone or a hardened OS and both of those use cases and the people using them likely aren't using biometrics. But that doesn't mean they have a good password either. People aim for convenience and less friction.
So let's think about what I am arguing here. I am arguing that a burner phone with nothing on it is likely more useful to a person worried about the police getting access to their device than a pin or password is. And that even if you do have a password there is likely a way for them to bypass it or there will be in the future.
You are arguing that even a weak password is better than biometrics, but that is in a singular instance where you are detained by or investigated by the police, and in that event you probably have a threat profile that would require more than just a password lock for your devices. Especially if you're using a weak password.