I Am Not the Crow ~ Viganò

Why is the great Sequestered Viganò in hiding?

Because Viganò knows he violated the oath he took:

Oath of Pontifical Secrecy

I, standing before His Eminence the cardinal secretary of state, having touched the sacrosanct Gospels of God, promise that I will faithfully observe the pontifical secret in causes and matters which are to be treated under the same secret, such that in no manner whatsoever, under any pretext, either for a greater good, or for a most urgent and most grave reason, permit myself to violate the aforesaid secret.  I promise to observe the secret, as referenced above, even in causes and matters that have been completed, for which such a secret is imposed. Whereas if in some case it should happen that an occasion bring me to have a doubt about the obligation of the aforesaid secret, I will interpret [it] in favor of the same secret. In like manner, I know that a transgressor of this kind of secret commits a grave sin.  So help me God, and these His Holy Gospels, which I touch with my own hands.