I think the micro organisms would be dead by now. They hate to be disturb particularly the root system. There is a very long large root. It goes deep to moisture. If that is cut it’s game over. if everything is done correct, on a transplant of that size its still 50/50. This tree has no chance unfortunately. They take about 6 months to die, they will die slowly. I know your optimistic so I tell you what you can do but it wouldn’t make any difference in this late stage. Go back and gather a meter square of the soil from where it came. Then get a large pot and replant it in there in that soil (Big plastic pot). Then once a week for Two weeks feed it a large bucket (6) litres Water to 300grms of brown sugar. Boil water and dissolve the brown sugar into the bucket. Make sure the water is room temp before pouring on tree. Then feed it monthly. The sugar is for the microbs. strong microns means strong tree. Then feed the tree water but try to use no fluoride in the water. Once a week but make sure there is drainage. In the pot it may concentrate better the soil than in the ground. I still think this is way too late. But it’s the best hope

By the way, mine are seed grown and haven't yet put on stems below the leaves. Both have multiplied their heads and are not quite as attractive as when they had single stems - what they really need is a good fire through them. Alternatively cutting way back, but I reckon fire is better, it's more natural for them. Also, a purchased 'bush' collected specimen (anything up to $200 plus) by a licensed collector, can take up to 2 years to die: they can be transplanted but care needs to be taken to disturb the roots as little as possible. B.

I currently have 3 grown from seed that I've had in for about 10 years. They took a few years to flower but once they did they developed multiple heads and while they still look ok, they aren't as attractive as when they had just a single head. Flower/seed spikes go up each year and are very bird attractive, when the spike falls or you cut it down, if you leave it on the ground to rot down seedlings spring up. The thing with grass trees is they like a fire through them every few years or if you can't provide that a good cut back will benefit - you may have noticed that after a bush-fire grass trees are the first plants to regenerate. I've managed to transplant them ok by restricting root disturbance as much as possible, however, they generally don't like being disturbed and can take up to 2 years to die as a result.

You could try giving it a 'burn-off', ie. putting newspaper all arond it and setting it alight, this has worked for me. Alternatively you could cut all the 'leaves' off right back to the main trunk, revitalises the plant in much the same way. Grass trees in the wild are accostomed to this - a fire around every 8 years or more.