Downplayed: Stacy dislikes supers and agrees with the registration act, citing several good reasons, while Heather stats more. Stacy is seen as more agreeable despite not putting forth as much evidence as Heather.
The work is meant to be ambiguous and make you examine how a Super Registration Act, if implemented, could work or backfire.
Although the character is very clearly a strawman, they weren't set up to be wrong or right, they were set up so that their attitude would help the plot along. Stacy's rant on the Super Registration Act and Heather's bickering was merely to convince Bob that there was no reason to rest in that small town.
Subverted: Stacy's points seems perfectly fine at first glance, but later it's revealed that her most compelling argument is flat out wrong or misunderstood.
Double Subverted: ...However, closer examination and Fridge Logic enable the audience to see the matter from her point of view and realize that one of her lesser arguments was even more relevant than her primary one.
Invoked: Stacy is brought in to argue in favor of the Super Registration Actbecause she knows all the perfectly reasonable motivations for it, despite the fact that those enacting it have twisted her words until her argument has Gone Horribly Wrong.
Defied: At one point, Heather says to Stacy: "Wait a minute. I don't agree with persecuting Supers, but you have a perfectly good point otherwise. Maybe it's time we discussed a third option?"
Discussed: An anti-Reg character states: "Don't you hate it when the bad guys make the most sense?"
Conversed: Two characters are discussing writing a plot about a Super Registration Act, but become discouraged when they realize there's no way to make the Pro-Reg side look wrong.
Deconstructed: The last act of the story reveals that it wanted the audience to react this way, and spends the rest of the movie showing the horrific consequences of agreeing with Stacy's point.
Reconstructed: ...But this scenario still turns out to be better, overall, than what would have happened otherwise.
Played For Laughs: Super-Duper-Man is seen flying off with a bank vault, and the crowd applauds him while Stacy desperately tries to argue why Supers should be registered.
Played For Drama: Stacy becomes the Unwitting Pawn of the supervillains pulling the strings; she was the greatest advocate of the Pro-Reg cause. Without her, the argument will crumble and the super-villains will be free to execute their master plan without distraction.