alt Hacker NewsYou cannot undo anything that's history, including not testing. If you missed a chance to get other tests or treatment early in life, you don't get the chance to fix that later either.
It would be easier to be cautious on penetrance, and reevaluate later, than to never collect the data and hope something changes. The number of these calls to limit our access to data are piling up, and they shouldn't be taken one at a time.
You're confusing mandatory public health level screening with opt-in personalized screening. The former is questionable at best - genetic diseases have very little external consequences, just the family / individual might suffer. Any argument about external consequences to neighbors/taxpayers slides us right into the dystopian future you'd like to avoid.
OTOH, we should have off the shelf genetic testing that sends you an SD Card / email and then deletes /anonymizes the results thereafter. You could bring that to a doc when you wanted to, and read the full results yourself. Very little harm in that aside from a de-anonymization campaign.