Before adoption of 2014 NEC this was not generally a requirement to use GFCI on a disposer, and still is not if it is not cord and plug connected with a 15 or 20 amp 120 volt receptacle. Local rules could vary.
2014 clarified that they wanted "within 6 feet of outside edge of a sink" to include kitchen sinks. Though they did not specifically mention receptacles in a cabinet within that 6 feet many interpret it to include those which would mean a typical cord and plug connected disposer would normally need GFCI protection.