It’s really not strange. Mifsud was not a “Russian agent” as Comey is a liar. He was an FBI possibly CIA asset and although not proven definitively YET, it will be.
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They wanted redactions because it is likely all their assets are going to have their covers blown. Likely there is a double cover, with one file naming all of them as Russian assets, while deeper, more classified files show them all as intelligence assets.
They will play this like Palme and accuse Trump of endangering national security by disclosing agents.
Trump endanger national security by exposing agents?
If we don’t name them, how are we going to know who to hang?