Note subtle cahnge in SRL maps recently, changed from a direct line Sunshine to Werribee to .......
Sunshine via Deer Park, Wyndham Vale, Black Forest Road, then looping back to Browns Road on the original Geelong line to reach Werribee.
This map has been floating around for a year, it's nothing new. Until Stage 2 is built to the Airport, I take anything west of that with a grain of salt. The planning clearly hasn't been done, and with MARL now going via Sunshine, SRL has little need to duplicate.
edit: Note how this map clearly shows MARL and "Metro Lines" where SRL is shown on the first map. At this stage, there is no SRL west of the Airport planned.