Yeah, I guess we've seen that picture before (in Anne Frank's flashbacks, etc.) If that was indeed Arden, why not use that as evidence against him?
Because "Anne Frank" was crazy, so nobody, not even Sister Jude, is taking her accusations seriously anymore. And "Anne Frank" was lobotomized, so she's in no position to try to prove anything . . . . .
Chances are, that photo is just going to get thrown into the trash with the rest of her Holocaust clippings.