It would double count emissions but it does mean that Australia could do more than just eliminate their own emissions, they could limit other countries' as well by stopping export.
Australia's coal industry provides few jobs, is heavily government subsidized (either explicitly or through direct infrastructure funding), pays little to no tax, and creates environmental harm that the majority of the electorate disagree with.
[Sorry HN: I know I should be supporting this with annotations but am time pressed today.]
Regional Queenslanders don't want to end up like the old coal mining towns of the UK, which still have not recovered from the mine closures in 1980s. https://www.theguardian.com/society/2017/aug/26/blighted-coa...
I'm not saying coal is morally defensible, but this is democracy in action.