This would ban legitimate uses only.

So not ban anything? Good.

Are the world police implementing this ban? And are they starting a world war to enforce it? Or how does this ban go into effect in your view?

Well we start with say you, you trade some of your bitcoin holdings, the feds seize your winnings, fine you and toss you in prison.

Why start with the person trading bitcoin holdings or any other action for that matter?

Why not just give the police arbitrary power to fine and toss in prison anybody?

Sounds like getting to that with extra steps.

Well what you're doing is actually a felony already.

https://www.federalcriminallawyer.us/securities-fraud/

How do they seize it? Say I’ve got a 256-bit number memorized and I live on a farm in El Salvador.

Is the US sending seal team 6 to interrogate every person trading bitcoin on earth? Or, is that maybe a bit unrealistic?

If you're a foreigner you're not violating US laws by selling your fraudulent securities. If you sell to a US citizen you aught to stay away from places with extradition treaties.

None of this is new or invalidated by magic coins in my computer.