It's his close relationship with the comedian and the fact he stated clearly it was in support for said comedian. Can't spell his name and can't be arsed looking it up.
He (comedian)has stated he created it as anti establishment rather than anti semitic salute but no rational person would choose a salute so close to the Nazi one if they didn't want the association made. Add to that his clear negative statements regarding the holocaust and Jews and no side track is acceptable.
Both Nasri and our very own Sakho have been photographed doing it too but both claim they were misled or just thought it was a popular gesture in France. Nasri did his outside Ethiad and Sakho states his was 6 months ago.
Anelka is on dodgey ground because of stating it's his close friend. I assume he has more knowledge of both it's meaning , effect and his friends political views.
The Nazi salute is illegal both here and in France.
Abuse based on religious grounds is also against FA rules. I assume if Jewish fans were present or viewing they could complain (Jewish council has I think, not sure if their Jewish lawyers association has yet though.....)
Martin Samuels interestingly calling for double the ban Suarez got based on the public nature (rather than private spat in a public place) of it and what it could potentially introduce into our game.....
Carlisle just as interestingly quiet about it, along with J Roberts, Collymore..
