Rusted staples. Pass.
Makes me think of an interesting point: Given the work already done on the book, would replacing the staples raise or lower the value?
And if the rusted staples were to be replaced with vintage staples from that same time period, would that be enough to push the entire book into PLOD territory, or would it still be considered to be a Blue Conserved book?
From the CGC web site:
Conservation Repairs
Tear seals
Spine split seals
Reinforcement
Piece reattachment
Some cover or interior cleaning (water or solvent)
Staples cleaned or replaced
Some leaf casting
So yes it would still be a conserved grade