The systemd thing was just a header, I don't disagree that it is a step towards age verification, but as far as I am concerned, there is no reason to take drastic measures until that header is actually used in the init system. Your earlier idea of determining the distros position I think will be a better metric as the distro is the more likely entity that will try to implement it.

As an aside, I actually like the systemd header since it will essentially standardize the place for age attestation which assuming your distro doesn't stop you, you could just pipe some bogus birthday into the field. This is of course assuming the init system doesn't implement the attestation mechanism.