(coexisting on another dimensional plane)
By 2257, he was a trusted advisor to Voq the Fire Wolf, who referred to him as "The Prophet" and "Master Sarek." When Michael Burnham came to warn the rebels of an impending Terran attack on Harlak, Sarek mind melded with her to evaluate her intentions.
Voq and Sarek heeded Burnham's warning and began evacuating, but were interrupted by Emperor Philippa Georgiou, who arrived in the ISS Charon and bombarded Harlak's surface, destroying the base and much of the continent. (DIS: "The Wolf Inside")