For 10 years Belize has an instructor training facility and a lot of Belizean instructors got their licences there. Scholarships have been available and taken advantage of.
I agree local Tourguides/Divemaster are best and most desired by tourist.
Instructors are a different matter. Allowing non-local instructors could do nothing but improve the stock by bring new and current information and techniques. Existing laws prohibiting them only depresses development.