That last point never appears in the article of course. Talking about the super leftists creds of a super-soldier only works if you forget the soldier half of the eqaution. You could maybe excuse the World War II escapades of the character, as long as you never look up the opinions of actual GIs, but you've got decades of imperialistic misadventures afterwards. That Chris Evans as Steve Rogers is filmed looking thoughtful and concerned about America building more and more superweapons doesn't change the fact said supwerweapons continue getting built - which only doesn't look supervillian-evil because there are nice two-dimensional alien invaders to worry about.
But that's getting off our main topic and dicking around in the muddy logic of the MCU, which only follows marketing logic anyway. Rather, the article's refusal to engage with the blood-soaked history of American foreign policy is what really makes it objectionable. The closest it ever comes is this swooning over an entirely fictional person:
Steve Rogers isn’t a warrior so much as he is a guardian. His first instinct is to throw himself into harm’s way in order to save others, regardless of whether he’ll survive or not. He quite literally threw himself on a grenade in order to save his unit during basic training. When it became clear that the only way to save the US from the Red Skull’s super-weapon, he rode that sucker into the ground in order to make sure that nobody else would get hurt. In fact, it’s pretty significant that Cap’s’ signature weapon is a shield, an inherently defensive tool... It doesn’t cut, it doesn’t thrust, it doesn’t penetrate, it blocks. It’s there to protect, not to destroy. And that shield is the symbol of Steve’s rejection of violence qua violence.
That all sounds nice and fluffy if you forget it was the exact character interpretation of decorated sociopath and racist Chris Kyle in the utterly forgettable American Sniper. Film-Kyle lacks the crude cruelty of the Kyle in his own autobiography, instead presented as just so concerned with protecting his fellow Americans... from the people whose country they invaded.
The various geek fandoms, whether superhero films or video games or whatever, never engage with these ugly realities. They can't as anything that breaks from the escapist value of the product will alienate potential customers. Not may, but absolutely will. You can't present an honest look at the world without upsetting someone, and that means one less source of revenue.
Geek cultural products may be creative, even inspired in rare cases, but they exist to serve a corporate bottom line. That market logic shapes them root and branch, and further shapes the fandoms surrounding them. An example: The Force Awakens is at best an adequate action movie, trading on nostalgia and the lack of Jar-Jar Binks to appear as something more grand. And also because something grand is what the fandom desperately craved, so anything not objectionably terrible was bound to be celebrated as "recapturing the magic."
That very magic was a fluke born of circumstances but it was a very profitable fluke, meaning many many attempts to do it again but built from a sterile marketing perspective rather than any imagination and soul. The MCU embodies this philosophy, constituted of two or three fun popcorn flicks and half a dozen snoozers - with more and more to come!
This is exactly what the fandom wants. Not just in films but in video games and comic books and the turgidly long fantasy genre that pretends to be real literature. Fandom is nothing more than consumption and brand loyalty, to which all artistic efforts are secondary concerns. Just because Superman isn't still telling you to "Slap a Jap" doesn't make him any less of a corporate pitchman. And just because the current movie incarnation of Captain America isn't bitching and moaning about liberated women doesn't change the fact he stands for the nation of pre-emtpive war and drone assassinations.
The fandom will not engage with this aspect of the character because it would go against the very nature of fandom: finding a safe place to hide from the scary world. That's the really toxic aspect of all these superheroes, the all-encompassing fantasy they promote. It's a reactionary brainwave that the fans crave, no matter how progressive they claim to be.