Really, the fact that the Metro train had stopped has got nothing to do with the fact as to why the V/Line train did not stop at the previous signal. Thus preventing this incident. IF there was a signal failure the signals are designed to go back to stop.
What signals are designed
to do, and what actually happens in the real world are not necessarily the same. I've had a signal give me a full clear road into a section occupied by an oncoming train. I've seen a 3-aspect automatic - with several other autos ahed of it - go from stop to full clear when following another loaded train home when it should have given us a caution indication first and have heard many other reports of wrong-side failures of signalling equipment from Drivers who actually experienced them. The signalling system is not infallible.
When passing a signal at stop, when authorized to do so, you are to proceed at a speed where you can safely stop short of any obstruction
Only for automatics... Speed beyond a Controlled signal may be track speed based on information from the Signaller.
If something like vandalism was a factor in this event, I hope it will prove to both the Police and the softcock magistrates that their slap-on-the-wrist treatment of scrotes has led to them taking bigger risks under the belief that even if caught, nothing will happen. Sadly something like that wouldn't surprise me.