They have been methodically canceling reservations a week at a time, why would they then jump forward an entire month? The optimist in me says....
Realizing that if they only open with 20-25% capacity then they already have enough bookings, so they stopped taking new June bookings.
Or... They got confirmation the NBA will finish the season at Disney and they needed remaining June capacity to shift reservations around to clear a resort or two for NBA players and staff.