A flaw in the criteria for the bechdel test is that stories are not often created as "every character has a story and fleshed out personality" but rather "I have a central story to tell and only the parts that contribute to that get in." It mistakes a lack of agency for what is more accurately a lack of screen time, and can easily be flunked due to a desire to keep superfluous conversation down. If the movie is about Hal Jordan growing into Green Lantern, then most cast will be there to aid that story, be it the girlfriend, the best friend, the brother's family, the trainer, the rival, the bosses, or the exposition giver.
For better or worse, y the Last Man is yorrick's story, not the story of the world and how it dealt with the gendercide (even though it was the most interesting part, but what can you do) so characters were placed as per what they wanted Yorrick to go through: who's going to try and kill him, who's going the try and screw him, with parts unrelated to Yorrick's journey not covered in a story that did cover years. I won't say it was the best direction, but it was the direction they took.