"Two Americas" comes to an end. American cnservatives have not been fully eviscerated. All the gnashing of teeth is pretty moot. Lets not beat around the bush, though. Brubaker took conservative anger at our government and used it to tell a story whose villains are examples of extreme conservative ideology. To be petty, Captain America arose out of anger at a form of extreme conservative idology, Nazism.
By the third act the arc has veered off of the the path of conservative anger at the current government and shifted to the culture wars. The real moral of this story is that, given we live in such a diverse country, we, sometimes, have to compromise some of our principals in order for us to interact with our fellow man. As long as people can exist and do not cause physical or devastating financial harm to each other, then you may have to give up the dream of homogeny. To tell that story necessitates a villain that may have a bit of a conservative lean to him. The culture wars are a conservative rallying point. The 1950s Captain America is a culture warrior taken to an illogical extreme. That comes into its sharpest focus when, atop the Hoover Dam, 1950s Cap begins screaming, "I don't want to look at this world and think it's right!" shortly before he attempts to blow it up.
I'm fine with Ed Brubaker using Captain America as a soap box for his ideals. It would not be a Cap comic without him fighting for something the writer views as an American concept. When Bill Willingham gets ahold of this comic, I won't begrudge him giving us stories with Flag Smasher on them. We live in a country, today, where audiences don't want to be given unbiased news reporting. Audiences actively seek out news that fits into their own world view or form opinions based on what they read out of the rare source of unbiased news. That is perfectly fine. Its how news has to survive, now. If people feel you do not accuratey report the news, they will find someone who they believe will, and that tends to be someone who presents news with a slant that they agree with. People like being informed, but also like being advised, and they respond to advice given by people they agree with.
If conservatives want a Captain America of their own, they are more than welcome to read Mark Millar's Cap in Ultimate Comics.