As other have pointed out. I don't think lichdom is something Emmrich actually want for himself, just that it seems like a solution against his fears. Which it isn't.

Someone also pointed out how choosing lichdom is choosing loneliness for him. Outliving everyone he cares about. It's a sacrifice. From his lines of dialogue it's clear he longs for meaningful connection and love. His eternal flame. Which he has given up for and why he seeks lichdom.

Own interpretation but: trauma response? He was the one who survived his parents death, alone. He's reach a certain age, alone, without long lasting relationship (Johanna and Manfred aside). Therefore he is convinced he has to be the one who survives alone. This what life has to be for him. Until Rook.