I'm almost 100% sure it's not Tiffins, it's that it's not ready...it was very un-Disney to give out an opening date this early (I know it seems that it's not early at all) but if you go see the progress on construction you can tell that there's still a lot to do. I'm not saying it's not opening April 22nd, I'm just saying that they don't want to have people buying preview and dinning packages without being sure that it'll be done.
They should've never announced the April 22nd date so early, they should've never hyped up a live chat about the show. And now it's biting them in the butt.