Personally I think the low $67M AUD~ Capex that has been previously identified in 2013 is a stand out factor - which also means quicker mine constriction time. CLQ which is also a Ni/Co Laterite deposit has recently reported a $900M AUD+ Capex for a 20 year mine.
In addition to this the process uses minimal sulphuric acid 25 KG/T. Compare this to CLQ's patented process which uses 275 KG/T++.
In regards to the 75% nickel that is not recovered - all not is lost as it will be stored so if a low cost solution does become viable it can be extracted. For the time being I believe the fact that Mt Thirsty will have it's most fertile production in the first three years is also a draw card. CLQ on the other hand will take 3 years to reach full production.