According to the Journal of Light Construction, the only construction in Florida deemed as critical is housing (because of the shortage of affordable housing) and road and infrastructure construction. Construction at Disney on the DCP housing and the removal of the bridge at Hollywood Studios fell under this exception.
Disney probably could have continued on other "in process" projects, but it is hyper sensitive to following these government decrees, and it probably doesn't look good if you are laying-off all of the cast members, you continue to pay construction workers. Stopping the work does conserve cash, but Disney doesn't account for new construction (capital expense) the same way it accounts for maintenance (current expenses), so you may see the capital projects start-up before maintenance (painting the castle).