This is correct, simply adding more Inferred Resource by drilling another 500 holes at approximately the same grades, widths and downhole depths does not tell us anything about the viability of the project.
Something as big as this would require several stages over multiple years to get close to the throughput tonnages they need for the project to be economic (? on the "economic"), hundreds of millions in drilling expenditure to convert the Indicated Resource to a Reserve, and probably several years of -ve cashflow to remove the overburden.
They could focus on the shallowest, highest grade part of the orebody initially to run the economics of a stage 1 starter pit to see if it flies, or incorporate everything into a larger study, but which would be based on many assumptions and probably wouldn't meet the criteria for a PFS, so that may be why they'll opt for an initial scoping study.
