What would be a suitable motor controller for this BLDC?
For low rpm or static positioning you cannot use a normal sensorless controller because the back-emf signal is too weak. However your motor has a built-in 14bit encoder which measures absolute rotor angle, simplifying the design of the controller.  

A PIC18F2431 should do the job since it has PWM outputs suitable for driving a 3 phase BLDC motor (through a 3 phase FET bridge). The encoder is read via SPI. You would not need the motion control module because the encoder already provides the required information. Firmware would be similar to a brushless gimbal controller, with the addition of angular velocity control.         

Be aware that brushless gimbal motors have high winding resistance, which results in low output power and poor efficiency compared to a conventional motor. They are normally powered at low PWM ratios to avoid overheating the windings.