If I had to take a photo of my genitals to sign into my own computer, promises against storage or sharing are not addressing my complaints about privacy. Asking my age is a lot less personal - but it’s still information about me, which this object does not need.

If you’re that concerned, leave the field at its default value, or (since its your PC and there will absolutely be a way to) set it to a null value. Or set it based on the amount of legal protections you want on your data, because that also appears to work.

‘I’m only okay with this idea because I know it won’t work’ is, just, why are we even talking? What is the function of an argument when you’re not listening to yourself?

Saying it can be bypassed doesn’t mean it doesn’t work. Like most safety and security measures, the point is to disincentivise and prevent errs of convenience - esspecially since children particularly lack impulse control. In the same way, having a railing or fence on a cliff won’t prevent people from passing, but will make them think twice. It doesn’t mean having that railing/fence is pointless.