The tactic of choice of the Left has always been to love America in the ethereal plane, in some abstract ideal that has never been realized, but because it could be realized, America is and has been a great nation. But the reality of America has been, and is, a long, sad history of genocide, bigotry, ignorance, hate, violence, racism, sexism, prejudice, xenophobia, homophobia, imperialism, religious zealotry, fanaticism, arrogance, and any one of another thousand faults and flaws.
When, and only when America conforms to my own, personal, subjective (which I see as objective) value system, will I give it my love and obedience. But my support for America or celebration of America, like all realities and truths, centers around me, only me. What I want. What I believe. Until it does so, I reserve the right to dismiss any loyalty to any celebration or affirmation of America. Until it conforms to me.
The irony, of course, is that Jane Kim can do just what she is doing. Not because America has existed perfectly only in some abstract spiritual realm of unrealized liberal ideals, but because it has been a real, solid, material bastion of the very freedoms that allow her - now, here, at this time - do refuse to say a pledge to that same country. Such is the post-modern mind that it never seems to grasp that, or feel it is something worth celebrating, or supporting, in the here and now.