I am confused at what the complaint is here. He did not stand for the anthem at the first, second, or third game but it was not noticed until the third one. He did not go to the media to complain or to explain, the media went to him. He did not make a scene, he did not interfere with his teammates or attempt to shout down those who wanted to sing or stand. He did not wave a flag of a country that fought against the USA. He sat quietly.
Just for further understanding. The third stanza of the Star Spangled Banner celebrates the killing of escaped slaves by the US military in the war of 1812. While rarely sung, there it is. Slaves who escaped from their "owners" were recruited by the British to fight and promised their freedom in exchange for military service. Francis Key goes out of his way to cheer for those black men to be killed, but never mentions being thrilled at white British soldiers being killed in the war. It is Key's big ending to his poem By the way, the Brits were good to their promise. All escaped slaves were at the end of the war apparently given the option of Canada or the British islands in the Caribbean.
http://www.pbs.org/wned/war-of-1812/...d-sailors-war/