Plus, he does go out of his way to screw the USA too. Which is why, save MAYBE the Nantucket series, the USA always ends up wiped out nearly to a man, and then replaced with some neofuedalist Mary sues who are all into neopaganism and lesbian sex
It's why I like all the fix fics for the Emberverse that nerf those tendencies right from the get go.
That's a pretty small sample set.
The Draka series. The Emberverse books. Pretty much every other book series isn't particularly hard on the USA. Peshawar Lancers (a one-shot book) really doesn't count, since it's basically inherently a British Empire story to begin with.
The Lords of Creation books have the US as the (rather more overt than in OTL) primus inter pares of the Free World, with only the Soviets as a counterweight, and all the bad people are foreigners (even the British guy).
ISOT is basically "Yankee Americans culturally or militarily conquer the entire planet". If you are reading any anti-American tone into that...you're smoking amazing stuff.
Conquistador is basically neutral (literally nothing good or bad happens to the USA), and is only stopped from being pro-American by virtue of the "Conquering American" faction that takes over Earth-2 happens to be rather villainous sorts (Rolfe and his faction are Reactionary agrarian aristocrats, and some of the others are basically outright Bad Guys).
Considering that the Emberverse books are basically post-apocalyptic adventures....they are no more "anti-American" than any number of Niven/Pournelle books (Lucifer's Hammer?) or the undying Post-Apocalyptic genre at large.
Neither are the books heavily drenched in "lesbian sex". Stirling, if anything, is rather gun shy about overt sexual imagery, and "Fade to Black!" is his most frequent tactic.....and there's not very many lesbians at all in the Emberverse (one, total, among the secondary cast, with less than half a dozen among the entire cast of named characters).
That's basically an unfair description of Stirling's body of work...akin to dismissing Elizabeth Moon's career as "a bunch of Women and Spaceships".
God knows I complain about some of Stirling's writing tics....but he's more or less innocent of what you are accusing him of.