Actually ... the real reason for the Pitt Water procedure was not Mt Lord itself ... rather the range of hills behind Mt Lord.
The procedure came about many years ago after a crew simulating eo and tracking straight ahead found that the terrain was out climbing the aircraft.
So the procedure was implemented to get aircraft to the east of Mt Lord and the other high terrain until they could climb to a safe level above the terrain.
BTW ... in the old days ... there was an exemption that allowed B727 to climb on rwy hdg
It is an old procedure ... that is not as relevant to new generation jet acft.