While The Hulk adds plenty of fuel to the fire when the Act is constructed, at least he's something of a known quantity to the citizens of the world, whereas the arrival of two new dubious "heroes" on the scene, in Scarlet Witch and Quicksilver, is certainly going to cause plenty of unrest. Though Scarlet Witch and Quicksilver will surely become fully-fledged Avengers in their own rights by the end of the movie, the fact that the group is only growing larger combined with the destruction caused by their fight against Ultron will only further the demand for superhero accountability. Plus, if the movie wants to have a little fun with it, they could even hint at some xenophobia on the part of the general public too, because in addition to being mutants, the pair talk with "funny" accents and aren't fresh-faced Americans like the majority of the Avengers line-up. Either way, their presence will only compound a public desire to get the superheroes under control.