not having read the full thread, here's what I think would probably happen:
The 2nd ammendment right to bear arms will be invoked as reason that supers are technically legal to exist. They are in effect a living weapon.
The military will want a squad of supers, as a secret weapon against enemies. They will also want a way to neutralize enemie powered forces.
law enforcement agencies (federal and local SWAT) will want supers teams for a similar reason. Since these are seperate agencies, they'll each want their own. Because the US military has a long standing policy of NOT being used as a police force in its own nation (there was much discussion about this after Katrina), the military's team can't be used.
local cops don't care about vigilantes. Especially if all they are doing is beating up crooks and tying them up. Sure the mayor and the DA may bark a lot about it, but the cops on the street have other problems to worry about. Just like they don't worry about finding the guy who stole your 8-track player.
If the supers stick to the "comicbook heroes code" then the public will like them and appreciate that they are the only force protecting them from super villains. The local authorities (DA, mayor, chief of police) may even condone their actions in some legally cautious speech.
Once a vigilante starts being involved in serious damage and deaths, then the cops have to worry about it and the public outcry will happen.
This is where ideas like mutant registration acts come into play. Because if gun ownership is regulated while respecting your right to own one, so can super powers. That will be the platform of political figures looking to get elected on fear ticket. There will be super villains supporting this, because it will help them find the super heroes.
As a creative person, I'd want to take a fresh approach to this concept. Super hero teams that are accepted by the public has been done (Fantastic Four). Super hero registration law politics has been done (Smallville, X-Men).
Since I live in a country where gun control laws exist and vary from state to state, while permitting people to own guns in most places (except DC, Chicago and New York as I understand it), people don't strongly resist these laws, nor does it stop being from using them to protect themselves.
So, let's live in a world where all the good guys registered their powers. Maybe its a secret database, because the government wants to protect privacy, while ensuring IT knows where the powers are used, in the event of crime, or national need. Kind of like a ballistics database crossed with the selective service registration.
Let's assume that the noisiest political problem is akin to what we get with the NRA or when somebody's committed crimes with guns and there's a wave of people shouldn't own assualt rifles histeria but nothing really changes.
In this world, super villains are basically terrorists, because the effects of their powers are about as devestating to the public.
Supers who fight them, if its a victory, will probably be lauded as heroes. Hereos who go on Punisher style killing sprees will be wanted. Heroes who do more damage than goood will also be wanted.
I'm not sure that reveals any new problems for PCs to explore, but it won't sound like a copy of x-men days of future past or the current season of Smallville.