This is a great point and got me thinking about other issues.
Usually the initial company has spent money proving up resources and compiled other data to establish "proof of concept" that there are viable mining opportunities. Mexus has foregone all of that and went straight to processing with the hopes it would produce and show proof of viability.
Well.... that hasn't happened. So now the incoming company has to put up the investment capital, time and other resources to collect that data. Why would a company do all of that just for the privilege to pay Mexus a royalty (or buy out the whole company) when Mexus has done nothing. The only value(asset) Mexus has here is the land rights. If there is an agreement to JV or buy out that would be the only thing Fresnillo would pay for.
The more I think about this, the more red flags that appear.