Hi Alesha! This is a great question, here is my best answer:
Clinically, the highest level which an individual can have a cervical spine injury and still be able to breathe independently is most commonly regarded as C4. Considering this individual's injury was to C2 and C3, you could expect him to be on mechanical ventilation. Depending on the type of mechanical ventilation utilized, and whether he is on a cuffed or uncuffed apparatus, his ability to speak might also be impacted. Otherwise though, he should be able to speak on his own.
This individual's motor function would be severely impacted, and we would expect him to be dependent for most activities. He would be able to speak, chew (mastication), sip, and perhaps blow but otherwise he would be extremely limited from a motor perspective. He would not have any usage of his upper or lower extremities, nor would he have the ability to hold himself upright easily due to lack of core muscle innervation.
From a sensory perspective, if this individual was presenting typically (meaning that he has no partial preservation) we would expect that sensory would be absent below C3, which ends around the very upper neck. Again though, this would depend on whether or not his injury was complete or incomplete.
From an autonomic perspective, this individual would be very susceptible to something we call "autonomic dysreflexia" which is a risk for any spinal cord injury patient above T6. This occurs mainly due to fecal impaction, and can be a medical emergency. Other issues that may be associated with autonomic nervous system dysfunction include increased susceptibility to the development of pressure wounds due to decreased sweat and sebum production, as well as difficulty with thermoregulation due to lack of sweating. This, in severe cases, can lead to heat strokes.
Lastly, let's talk about bowel/bladder and sexual function. Because the urogenital system is innervated primarily by lower sacral segments of S2-S4, we would assume that this individual has an "upper motor neuron" type presentation of a spastic/reflexive bowel and bladder. This can lead to difficulty with voiding both bowel and bladder, and can increase risk of incontinence or impaction. Often times, these individuals have to learn to use maneuvers like the Crede maneuver or even digital stimulation to void.