Then that is the 18+ age signal. "This user is not covered by age restrictions" implies they're older than 18.

And as the law says...

(4) A developer that receives a signal pursuant to this title shall use that signal to comply with applicable law but shall not do either of the following:
(A) Request more information from an operating system provider or a covered application store than the minimum amount of information necessary to comply with this title.
(B) Share the signal with a third party for a purpose not required by this title.