PA discount rate reflects time value of money. NOT an exact science, and clearly does not include added long term risk discount factors or upsides. PEA says basically using these assumptions here is the PV of the cash stream. Very conservative considering the resource will grow, and known downsides as stated have already been built into the assumptions used as opposed to risk discounting. A good example is resource price used. Serious investors might run their own sensitivities, especially on price, grade, production volume, production cost and capital cost. If you thought LT bond prices are going to drop, maybe use a higher discount factor. These numbers tell me the resource itself is economic today , unrelated to the share price or market cap.
Certainly one hurdle considered pre-requisite to a main listing but with no direct link to sp.