"bad apples" = one rotten apple ruins the bunch.

There are no "good apples" the article itself shows that other "apples" were helping him illegaly surveil. The "good apples" thought it was a good idea to give every apple access to a problematic system.

There are no good apples if there's a rotten in the bunch, we need public oversight of the only people that are allowed to enact violence on behalf of the state.