[jheriko]

i'd guess the investor is the sort of company with standard policies and practices that include signing of NDAs for even potentially sensitive information to protect themselves in a paranoid way. lots of people 'just doing their jobs' will ask you to sign an NDA without much thought about what it might mean.

never attribute to malice, that which is more simply explained as incompetence.

if its not that sort of company, negotiate it away... although it sounds to me like you aren't keen anyway.