The canal is a military installation built by the military.
It was built to give the navy access to the Caribbean without having to go through Belizean waters.
The canal will only accomidate shallow draft boats. Access to it through the Bay of Chetamal is also very shallow. There is little intent at this time for commercial/tourism traffic.
The reef wasn't damaged during construction.
Building the Basil Jones airstrip into an airport able to handle commercial traffic is a financial undertaking that neither the GOB, private sector or both combined could bare, not now, not in the near future.