I am also very confused about the slug part because the dot is supposedly killing in alphabetical order. Yet the dot was going to have her walk into a slug in the elevator a while before her name was up.

Apparently this entity cares so much about the alphabet it stopped targeting her to go after the september guy so what gives?

Someone theorized the slugs may hold you and kill you off when its your time but the list the dr uses to realize its in alphabetical time isn't time of death, its time of disappearance. These slugs do capture on video so If people cant have been alive inside a slug without anyone or themselves noticing.