A pardon cannot unring that bell. He can be called as a witness with *immunity* to tell the truth (Pardon doesn’t create immunity)...
Note: SDNY hasn’t made a deal with Cohen probably because he hasn’t given them enough reliable info. That suggests Manafort gave up more significant info already.
Would immunity have to extend to perjury/obstruction?
And if not, could he plead 5th?
If Manafort gets broad pardon (a big IF, and ignoring his huge state crim liaility for now), and then feds grant him immunity to compel testimony, it seems he can change his tune from proffered info w/ impunity for obstruction, but...