So turns out that Disney hasn't actually "fallen behind" on TSL. It's right on schedule, but for all of the wrong reasons. As you guys may have noticed in the past few aerial updates, there's been little progress. This is because Disney is again falling into the habit of spreading out costs.
Also, why open the land on June 30th? Well, as it would not so coincidentally have it, that's the last day of Fiscal Quarter 3, meaning that they have the entire quarter to spread out construction costs, with minimal operating costs. Then once Fiscal Q4 starts, construction can pick up on things like Rat and other projects.