What is the significance of the password?

The password "Dashwood" is a reference to the protagonist of Jane Austen's "Sense and Sensibility" and it serves as a parallel between the novel's conflict between sense (logic, propriety, and thoughtfulness) and sensibility (emotion, passion, unthinking action) and Harold's internal conflict between letting the ASI's "live" (sense) or letting Humanity fend for itself (sensibility), opting for the latter in the end. Also, the book is the one that he used to propose to Grace back in the day, which makes it even more meaningful.

Reference

I know really late to this party but just watched them all and i would say its a different answer, I think Dashwood is Harolds original surname, since in the same episode as the grace proposal there is also reference to harolds original name from nathan and how he would tell her it and the implications around it also if anyone knows even harold, what his original name was and its not likely something he would ever forget what with him using birds as a way to remember him. https://vignette.wikia.nocookie.net/pediaofinterest/images/1/15/20170102_23502.jpg/revision/latest/scale-to-width-down/1000?cb=20170103055757

also dashwood fits this