Actually it should help with both, because a on-island terminal would also provide LNG storage capacity which would buffer short-term price fluctuations. We have zero such storage.
Again, our poor decision making around national infrastructure is on our governments. They left have left us completely exposed to international markets.
A lot of it relates to the planning process, they do keep trying to build things. One could argue that this is also their fault (and I do!) but there are good historical reasons (cough ray burke cough michael lowry) why we've ended up with such a bureaucratic, byzantine planning process.
Yes, there are many problems with the planning process, but as you conceded in another comment, the actual reason that we don't have an LNG terminal is that Eamonn Ryan nixed the possibility.
As usual with the Greens, perfection was the enemy of the good.