If it's not (fully) your code, you aren't free to set the licence conditions; Linus can't do that without getting approval from 100% (not 99% or so) of authors who contributed code.
What one can do is add an informative disclaimer saying "To the best of our knowledge, installing or running this thing in California is prohibited - we permit to do whatever you want with it, but how you'll comply with that law is your business".
It also helps when you take an offender to court. If I contribute to a project but don't assign copyright, then they cannot take offenders to court if my code was copied illegally. The burden is on me to do so.
Of course, all code released prior to the change still remains on the original license.
A "Linux distro" is not the Linux kernel. It's possible for some distros to add such license terms to their distribution media, but others like Debian and Debian-based ones adhere to the GPL so no go.
"Every OS provider must then: provide an interface at account setup collecting a birth date or age, and expose a real-time API that broadcasts the user's age bracket (under 13, 13 to 15, 16 to 17, 18+) to any application running on the system."
Debian, Ubuntu, etc., they'll all fall right in line because the clear and immediate losses will outweigh any PR issue.
6. Each time you redistribute the Program (or any work based on the Program), the recipient automatically receives a license from the original licensor to copy, distribute or modify the Program subject to these terms and conditions. You may not impose any further restrictions on the recipients' exercise of the rights granted herein. You are not responsible for enforcing compliance by third parties to this License.
5. No Discrimination Against Persons or Groups
The license must not discriminate against any person or group of persons.