This is from a completely business perspective, but this whole "ADS" conversation seems to be the highlight of discussion for the hardcore Halo fans. GAF, Waypoint, /r/Halo, Beyond, etc., whatever Halo community you go to right now, this is the prominent discussion. Why kill the buzz? Let the audience wonder, I suppose. Give them something to talk about until it's time to reveal the truth. "All publicity is good publicity."
At the end of the day, I don't see ADS being in Halo. But then again, we all had the same argument for Sprint.