Of course I'm getting my dates mixed up.
The choices were actually.
1. Register.
2. Go to prison.
3. Give up being a super hero.
Firestar opted for #3 and immersed herself in her studies at college, after which no one bothered or hunted her (although I'm guessing that someone would have followed her for the rest of her life to make sure that she wasn't cheating on her vow.). Option three seems a little wavery to me. Didn't they want to register everyone with powers and not just everyone in a cape trying to save the day? And should electing to give up superheroing be that grounded an option after Tony figured out SPIN technology and could "stop" anyone he felt like from having powers. Which is the difference between Abstinence and castration.
Or you could do what Ben Grimm did.
Go to France.
#### you USA!
(The US Government emptied his bank account in retaliation that had a hundred billion dollars in it.)
Oh.
Maybe Ben is waiting?
What happens if when he sues for the return of all that cash after the government has spent it on something stupid like tax breaks for the %1, and they can't afford to live up to their debt to the Thing?
Ben Grim, King of Wyoming.
(Never going to happen.)
Although, the Fantastic Four's Loyalty to the American Government has to be running on empty after the Government took Franklin (Did they get Valeria? She'd been living in Latveria and might have missed that.) and the rest of the Future Foundation into Foster Care. If Susan was smart and wanted her kids back, she should have raized Congress and flung the white house into orbit. Don't kill a million soldiers when you can win a war by getting one general into a titty twister until he surrenders.
So everyone in the 42 prison, they could agree to leave US territories, or agree to stop using their powers in public/fightcrime/save civilians from natural disasters like volcanoes, or they could volunteer to have their powers removed with spin or another less invasive method.
Registration meant conscription into S.H.I.E.L.D. and placement into the 50 state initiative. They told you were to live and paid you handsomely to follow orders but punished you if you didn't, no different from being in the army other than instead of a cot, you got to live in a mansion with a full cable package until you were told that it was time to save the day.