In summary:
a) Melbourne Airport Rail Link was a 'thing' before the Suburban Rail Loop (current state and federal governments each committed $10 billion to it).
b) The Suburban Rail Loop was a policy under wraps not devised within 'traditional' transport departments (but the state's own land development agency: Development Victoria [side point: the public transport minister also has oversight of that portfolio area[).
c) A few weeks after the Suburban Rail Loop was unveiled, the operator and owner of the Melbourne Airport lease came up with its own private proposal for the Melbourne Airport Rail Link, pledging that the link would be open and potentially hook into the SRL.
d) the SRL has now evolved so that we know what's happening in the West - which when first unveiled was really undercooked.
e) Victoria's state elections have been held every 4 years on the final Saturday in November since 2010, the next one is Saturday, November 24th, next month.
Melbourne Airport expansion plans context (Rail stuff toward end of video)
• Video Link
AirRail Melbourne proposal which may or may not form part of the eventual Airport Rail Link (and therefore Suburban Rail Loop).
https://www.airrailmelbourne.com.au/