Scratch that since a new report from the Wall Street Journal is now teasing early October as the official debut date for the NX.
Assuming its true, maybe Nintendo didn't want anything else from the Tokyo Game Show to share the media spotlight with the NX had it occurred next week. Also could be entirely related to them wanting to pull another "The Wizard" moment by using the upcoming Splatoon tournament for its official debut.
http://www.gamespot.com/articles/nin.../1100-6443403/