That was back when it was meant to be a launch title. As per 343i the game has been "content complete" for a while, Joe Staten even said that he played through the whole campaign when he joined in August. They would have spent more than a year polishing the game by the time it releases. So, RT is probably available at launch.
When they say content, they mean levels, weapons, enemies, etc...
RT would fall off that category and fit into "tech" or "features", more particularly into render tech, and maybe some tech art, if they need to tweak the level data or even lighting art.
Now, I imagine that all this departments have been very busy improving the game lighting, textures and details so I am not sure they have had time to spend on RT (unless they would had spent the time on RT as part of the visual upgrade, but then again, I doubt that because the game is also for last gen and they should not base their visual upgrades on something exclusive for next gen)
My bet is that they will add RT in one more years time.