It's more likely to be an issue for distributions like Debian, Ubuntu, Red Hat, etc.
Although, if I'm understanding this correctly, I think all they would have to do to comply is have something during installation that asks for the age category, and write a file that is world readable, but only writable by root that contains that category that applications can read.
And then another state will pass a law mandating scanning of all local images, and another state will want automated scanning of text, and a different country will want a backdoor for law enforcement. We have to stop this here and now.
That is already way too much as far as I'm concerned. It's not that it's difficult, it's that it's arbitrary and a form of commanded speech or action. Smallness and easiness isn't an excuse.
If you write a story, there must be a character in it somewhere that reminds kids not to smoke. That's all. It's very easy.