I think Chris is equating it to the bank deposit rate, which I've never heard of before. He's also omitting inflation on nominal cash flows, which doesn't make sense, but who am I to question this approach? The best way to look at it is the rate of return at which you're willing to part with your money today to invest in MYL as a mining project. It looks like Chris is happy to part with his money on zero rate of return.
In any event, it's all relative so if he uses 0% discount rate for Bawdwin, he should be using the same discount rate for other comparable projects, which raises the other projects' absolute value too.
IRR is probably a better metric to use to kill off this debate as it's the rate at which NPV = 0 and there's nothing we can argue about there.