Davidash, the loadfactor means very little, its the yield that drives the profitability on the route. One needs to ask how heavily they are discounting tickets on the route to fill the aircraft. For instance, this is what Tuesday's (tomorrow's) flights are looking like:
Cheapest tickets:
CPT-DUR:
SA600 R650, SA606 R650, SA612 R650, SA616 R650, SA620 R2350
DUR-CPT:
SA601 R2350, SA607 R650, SA613 R650, SA617 R650, SA621 R1250
So the cheapest tickets are available on 80% of the flights one way, and 60% on the return, compare that to JNB-CPT (a flight of almost identical length) where the cheapest ticket is only available on 5 out of 21 flights one way, and 4 out of 21 on the return! What this means is that the DUR-CPT flights are yielding poorly.
Secondly, even if the early morning flights are full and yield a lot the route is not viable for one flight a day to a network carrier.