Final answer:
The Daodejing does not contain biographical information about Laozi, and his existence as a historical figure is debated, thus studying it will not inform your roommate about Laozi's life.
Step-by-step explanation:
The primary issue with your roommate's plan to study Laozi's life story through the Daodejing is that this classic text does not provide biographical details about Laozi. The Daodejing is a compilation of philosophical aphorisms and teachings associated with Daoism and isn't meant to serve as a historical account of Laozi's life. Moreover, the existence of Laozi as a historical figure is a matter of debate among scholars, and much of what is referred to as his life story is shrouded in mythology and developed over time rather than being part of the original text.