Bucky
Desparate to spit the dummy whenever someone disagrees with them, American rightwingers will go as far as to label Captain America Un-American. You’ll notice that, whilst they’re busy complaining, they’re not above putting a link to the offending stories on Amazon in the hope they might make some money off them. (My link to the same book, give me the commission, I deserve it more than they do.)
If you’re going to have a character who so obviously represents a country, then some creators are going to use their stories to express opinions on that country. Cap’s been there before. I’m not a big Cap’n Yank fan, so I did some research.
In the early 70’s Watergate made it onto the pages of the comic as Cap found the president was working for the Secret Empire. Following the suicide of Nixon El Pres and his replacement with an actor, Steve Rogers (CA) stopped wearing the flag and wandered around the world as Nomad fighting evil corporations. Of course, he came back after a while, when one of the people acting as Cap was killed. He quit again in the 80s when ordered to work directly for the Government.
Captain America History 101
Commentary on The Truth, which you can also buy on Amazon