"It has always been legal to pipe radioactive gas into US homes where it can be inhaled and get to work causing cancer"
This is arrant nonsense. No one breathes natural gas. It is burned in a furnace or hot water heater and exhausted outside the home--at least I hope so, or the CO will get you long before any entrained radon will.
My point in citing that link was not that natural gas contains less radon than air, but that its use doesn't contribute materially to the radon content of ambient air.
What you should consider seriously are the consequences of a philosophy that makes the perfect the enemy of the good. If you shut down natural gas because you are worried about its radiation, you'll end up with more coal--which has radiation concerns of its own--and fewer renewables, because wind and solar, being intermittent and cyclical, need natural gas backup. There are no perfect energy technologies in the real world; it's all about trade-offs.