The Sit Heard Round the World

Once upon a time a group of British colonists decided they had had enough of the King of England and his taxes.  The decision was by no means unanimous, but once a revolution gets rolling it takes on a life of its own.  In the early going discontent was expressed through public acts of protest like throwing tea into the Boston Harbor.  The Crown was not so fond of this sort of behavior and so they responded with punitive measures, which became known as the "intolerable acts," and things got more heated from there.
Eventually King George III learned that fighting wars across oceans is really expensive and decided to accept the defeat that saw the sun begin to set on the great and glorious British Empire.  Hey, wow, the little guy won against the big, bad British Empire.  They wrote up a Constitution and dedicated themselves to some noble truths about freedom and equality and such.  They, somewhat naively, thought that would be that.
They ratified their Constitution on September 17, 1787.  Seven Articles of fairly concisely stated structural principles for a democratic republic. In December of 1791 that basic document was amended with ten further principles known as the Bill of Rights.  That's less than five year later if you're a numbers type.  The first of those amendments went like this:

Congress shall make no law respecting the establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press, or of the right of the people to peaceably assemble, and to petition the Government for a redress of grievances.

That is as close to a sacred edict as you are going to get in our world, and it is a good thing to have written into your legal code.  But it is also going to be a hard thing to live up to, because sometimes people are going to want to say things that Congress and maybe the nation as a whole aren't going to love to hear.  They may also say things that aren't particularly well thought out.  They may lead with their emotions and not with their clearest thinking (I do that here sometimes).  But it is as close to a core principle of our nation that people are free to worship as they choose and to say what they want.
At times there have been limits set on those things, like obscenity laws and the Espionage and Sedition acts of 1917 and 1918 respectively.  Most of the time, our legal process has found that free speech and freedom of religion are worthy enough causes to justify the discomfort that their exercise sometimes causes.  In other words, it is a worthwhile value to allow people to say what they want, even if that something is offensive.  We allow the Klu Klux Klan to have rallies, we allow Neo-Nazis to fly swastika flags, we tolerate lots of things we collectively don't like very much because we value the freedom envisioned by the Constitution and the Bill of Rights.
Enter one Colin Kaepernick, quarterback for the San Francisco 49ers.  At a preseason football game, Mr. Kaepernick decided not to stand up for the National Anthem.  He planned it ahead of time and issued a statement concerning his purpose for not standing:

I am not going to stand up to show pride in a flag or a country that oppresses black people and people of color.  To me, this is bigger than football and it would be selfish of me to look the other way. There are bodies in the street and people getting paid leave and getting away with murder.

I am not going to defend, refute or otherwise comment on Mr. Kaepernick's reasoning.  I am going to absolutely defend his right to plant his tookus on the bench during the National Anthem or the Pledge of Allegiance or any other time he wants, for whatever reason he wants.  He was not disrupting a military funeral or even creating much of a scene.  He was not inciting violence, or calling for the assassination of an elected official or committing a treasonous act.  In fact, if no one had asked him about and put it on the TV, if it wasn't for social media, would anyone really have even noticed?
You can be upset about what Kaepernick did, apparently a lot of people are, but most of them seem to be using some sort of patriotic line of reasoning, or stating that he's disrespecting those who have suffered and died for our nation.
I would say, to the contrary, that he was actually honoring those who serve our country and "defend our freedom," to use the old saw, by exercising that very freedom.  He did not break any laws, or do something publicly offensive, he simply sat.  He used the position of visibility that our obsession with sports has given him to make a statement about something he feels is wrong with our society.  If you disagree with what he said, fine, but please America, let's be proud that he is allowed to say it and sit it.