The Duke of Sussex delivered a speech to the U.N. this week -- in observance of Nelson Mandela Day -- and one of the things he said was the reversal of a federal right to an abortion was among the many things he considers a threat to freedom.

The others ... COVID, the war in Ukraine, disinformation and climate change -- all of which he said were among the top perils facing the world. But, McCain thinks he's misinformed.

In a piece written for Daily Mail, she slams the ex-Royal for what she considers virtue signaling -- especially on the Supreme Court's Roe decision ... which she says isn't a threat to democracy, but more so an exercise in it since it gives the power over that issue back to the states.

McCain, who is undoubtedly conservative, argues Harry is ignorant because he isn't an American citizen -- but likes to play one on TV now that he lives here with his wife Meghan Markle. She cites other times where he's admitted ignorance to the First Amendment.

The whole op-ed goes on to call Harry "woke," rhetorically asking if America isn't good enough for him ... why is he even here? She also cites his and MM's accusation of racism within the Royal family to make her point.

Indeed, it's a Harry-bashing think piece ... and in the end, McCain asks this of the Duke: "Maybe he needs reminding that he is a guest here and not a guest who has been universally embraced by the American public."

She adds ... "So here goes: This is not your home country. In fact, my country went to war against yours so that we'd never have to be subject to a royal lecture ever again."