This is what Kaepernick said after the first time he didn't stand: "I am not going to stand up to show pride in a flag for a country that oppresses black people and people of color. To me, this is bigger than football and it would be selfish on my part to look the other way. There are bodies in the street and people getting paid leave and getting away with murder." While I disagree with pretty much everything he said, and even how he is protesting, I also disagree that it is overtly disrespectful to the military. His protest clearly had nothing to do with the military and his intentions where clear. That said, some people in the military felt disrespected by it, while others did not. So it's in the eye of the beholder as to whether or not it's disrespectful to people who have served. But his protest was clearly to bring attention to police shootings and I don't think he intended to insult anyone other than the police, and even that was limited to police who shot black people.