There are several different issues here. One is that there is a difference between a work permit one gets for working as an employee in Belize and the privilege of opening a business as an investor.
As a resident investor bringing new jobs to Belize you can do things a simple employee cannot do (though not everything -- you can't be involved in commercial fishing, bee-keeping, sugar cane production, for example, which are fields protected for Belizeans.)
As a resident investor operating a resort you can run a restaurant, bar or retail shop which normally you would not be able to do.
But in some cases you would have to get permission of the local government council to operate a business. For example you can't just go down to Placencia and decide you want to open a jet ski business -- you're going to have to get approval from the Placencia village folks.
Of course as a resident under the Qualified Retired Persons Incentive Act you can't work or run a business in Belize at all, though yhou can live in Belize and operate a business in another country.
But as someone else said nothing in Belize is cut and dried. There are guidelines and rules, but who you know, or who you don't know, are at least as important as the official rules.