Deification—this is something utterly beyond the imagination of ordinary people.
Whether it's symbolic deification or actual deification, neither is within the grasp or comprehension of the average person.
Misumi Mikoto knew that Chen Yu was a Demigod. Even after becoming a Necromancer herself, she had harbored dreams of deification. But she felt this was something too far removed, both from her and from her teacher.
Although Chen Yu, in some sense, wasn't too different from deities, through her study of necromancy, Misumi Mikoto clearly understood the vast chasm that existed between Demigods and True Gods.
So, even though Chen Yu could easily summon Demigod-level Ship-girls and had given her two, she never thought her teacher could truly ascend to the level of deification.
As for herself, while she had entertained such fantasies, deification was not part of the plans Misumi Mikoto had set for her future.