I assume there is a tipping point beyond which it is impractical to defoliate and treat every single tree in a region. Possibly Hawaii passed that point.
What they have proposed is drastic. Remove all new growth (that is still green), defoliate the tree, spray and inspect over several weeks as new growth emerge. Take the removed materials away disposal (likely burning).
... not just in commercial orchards, but in dooryards too. That is a huge undertaking.