It was his defence and that is what The FA found him guilty of!
"using abusive and/or insulting words and/or behaviour ... which included a reference to colour and/or race."
FA rules on abusive behaviour and discrimination
E.3 (1): A participant shall at all times act in the best interests of the game and shall not act in any manner which is improper or brings the game into disrepute or use any one, or a combination of, violent conduct, serious foul play, threatening, abusive, indecent or insulting words or behaviour.
E.4: A participant shall not carry out any act of discrimination by reason of ethnic origin, colour, race, nationality, faith, gender, sexual orientation or disability.