Every single component in the DIY pistol kit is legal.
No question, Supremes made that clear.
But selling all parts together is not legal, as it's too easy to build a firearm.
I don't happen to own any classic muscle cars at this time, I'm not in the market to buy their components.
But a friend attempted to purchase parts for their 72 Challenger, and they wouldn't ship to PA, because we mimick Kalifornia air pollution and vehicle laws.
IE, a requirement for all factory smog components for inspection.
Because the ruling you are advocating won't do a fucking thing to stop, or prevent a crime, it will only stop people who are already legal to purchase a firearm, making them go through another step, which is not needed.
Surely, if you have time for a Trump Golf tracker, you have time to be concerned about the children, (Albeit black and inner city) who are still as likely to be murdered by this meaningless ruling.