It seems shortsighted to define the age bracket API specifically around California's chosen four brackets. Why not merely return two integers bounding the age bracket, so that the API can adapt to different regulatory environments?
I'd personally love to see the fireworks if Microsoft refuses to implement this, and takes no action to prevent Windows from being imported into or used in California?
How could California plausibly respond that would harm Microsoft more than its own economy?
Microsoft would never do that. They'll rebrand this as "Defender of Verification," package it into a bigger deal where you have no idea what you're buying, and then find a way to cram AI into it.