Before the ceremony he sits among other patriars on the pews in central nave of the Audience Hall.
After the ceremony ends, Admiral Hullhollyn moves to the norther nave and stays near the first table with refreshments. If spoken with, he says that Ulder Ravengard, as a good leader, has chosen the right moment to step aside and let Gortash rule.
If choosing to confront Gortash, the party can find Admiral Hullhollyn along with all other invited guests and their retinue slaughtered in the Audience hall.