Mexus did not elaborately plan to wait until gold prices spiked to start selling and producing gold. They haven't sold any because they haven't been able to produce any to this point.
Mexus has sold properties at more than fire sale prices (and supposedly reacquired after the buyer defaulted). Additionally, Mexus gave up 50% interest as part of a JV deal that also fell through.
Mexus is doing it on their own now because after two failed partner attempts they couldn't find anyone to partner with them.