Pre-emptively of course for Obama's involvement in the whole Flynn, Russian collusion nonsense, nefarious Coup attempt. Wipe the slate clean. 1. We don't go after previous presidents. 2. Difficult to prove how active/passive Obama was in the whole matter. Obama could have had legitimate concerns initially, but once it became clear that there was no "there" there, he should not have allowed it to continue. 3. While publicly taking the high road, this is a brilliant political maneuver. 4. It's the perfect response to Pelosi's comment that Trump is Forever Impeached. Obama would Forever Be Pardoned, and that is enough. 5. Time to move on.