As of last week they expanded the definition of what they allow, explicitly mentioning coding

http://help.twitch.tv/customer/portal/articles/2176641-creat... Q. What if my creative broadcast is gaming-related art, game development, programming, or involves creation of music? A. You are free to choose whatever you think is the most appropriate category for your creative broadcast, so long as you adhere to the Rules of Conduct for the category when doing so.

Q. Does all Creative category content have to be gaming related? A. No, you’re free to broadcast your creative process for any genre!