Yes, YC specifically posted about founder ethics a year and a half ago.

https://blog.ycombinator.com/founder-ethics

https://www.ycombinator.com/ethics/

  "To maintain our community, if a founder behaves 
  unethically during or after YC, we will revoke their YC  
  founder status. This includes access to all Y Combinator
  spaces, software, lists and events."

  "We will stand behind you no matter how much your company
  struggles, as long as you behave ethically."