I just had a theory: Could this have been timed with everyone's guesstimate that the most recent budget was that of a government going to the polls this year, and if it doesn't get passed by the Libs it will be a black mark to put against them come voting time?
Plausible. However genuine this push is, Labor know they wont get it through without an LNP conscience vote, so its likely to be defeated. If they genuinely cared they would have done so when in government.
It's political opportunism by the party, riding on genuinely held beliefs of some of its members.