This is just my opinion... but if NASA wanted to hide this "alien claw", It would seem they would have published this version of the photo:
Nothing to suspect, nothing to attract attention and no claw.
If NASA truly wanted to hide objects from us, they simply would not release them for public view. To show a part of an "alien claw" to the general public (assuming they are trying to hide it) would require NASA to be dumber than a politician.
Besides, in the "claw" photo:
The bottom "finger" is just a shadowy part of the upper lip of the partly crumbled ledge (see yellow line following the ledge):
M