Wrong. As Flanagan explains, Alternative Vote (which the Liberal call ranked ballot) would give them a short term boost. This was confirmed by the Broadbent Institute's study on the 2015 election. 

The Liberals killed it because the all-party committee recommended proportional representation, which puts voters in control in elections. Imagine a voting system where you can actually punish a party that breaks its promises! That's anathema to the Liberal establishment.