Pictures don't mean a thing, especially considering that there have been a few pictures placing Sanders where he was never at, like in Selma and leading a sit in at a college. The lies and misrepresentations being floated are only making things worse for Sanders.
I may be wrong here, but that picture was never proven to be fake. The photographer of the Selma picture also himself said that the man in the picture was Sanders. Nice try, though.
Sanders was never in Selma, even he has never said that, but his supporters claimed that. As for the sit in, the man in the picture was not Sanders and several people stated that it wasn't. Sanders initially claimed he wasn't sure and apparently now he says for sure that it was him.