Why not? The FA can do what the **** they like. On the balance of probability, the FA decided Suarez said a racist comment, so banned him. On the balance of probability, they have now decided Terry said a racist comment, so have stripped of the captaincy. Argue it to your heart's content, but they're well within their rights.
They're within their rights to strip him but if he is found guilty they will be under pressure to re-instate him and be open to prosecution. They may have their own rules but they are not exempt from the law of civil liberties and contractual agreements and libel.
