In that still photo, he was motioning what happened to his eye. That was one of the many times the police paraded him around in front of reporters because of concerns they were mistreating him. Here is another time he was asked about his eye. The photo was not a communist salute. You fell for propaganda.
https://youtu.be/4FDDuRSgzFk?t=2m59s
Oswald said he was “just a patsy” - I think if he really was the one who killed Kennedy - being as how he was in custody, why not take the glory for killing the capitalist JFK.