I think you're misreading it. It doesn't ban Linux from providing age collection and verification. It makes it a choice, rather than mandatory.

I would expect that Linux users want access to age-verified apps just as much as other users, so such a signal will be available.

Also, you're being overly pedantic on the language used. It transfers liability away from the service, more easily allowing operation in about half of the states. "age verification" is a fine lay description.