But that assumption fails to explain all the aspects of this exchange that remain a secret to everybody.
The biggest SECRET to us is: how the heck did that Moblin get down there? In many cases, you have to bomb through solid rock to find him. Does he have a secret entrance elsewhere? Or has he been imprisoned in stone magically? If so, how did he have air to breathe and keep those two flames going? Are these Moblins the Hylian equivalent of a toad sealed in stone? If so, Link can't help but keep the circumstances of their predicament a secret, because he wouldn't actually know how that happened.
If it's not the nature of the hideout, maybe it's the location. The Moblin could be avoiding creditors by living in hiding -- in which case his unbidden payoff of Link provides further evidence of financial irresponsibility. If the Moblin had thought about the situation for a minute, or even just asked Link, he would have found out that not only is our hero not going to go blab to Ganon or the credit card company because of his integrity, he's also mute.
Or is the secret the passing of money? This is the obvious choice. "Don't tell anyone I gave you this." We assume, then, that the Moblin has some reason for helping Link defeat Ganon. We suspect that the Moblins resent Ganon for taking on the appearance of a giant, obese Moblin. Or maybe the cave-dwelling Moblin wants Link to go get him some cigarettes, but never finishes the request due to Link taking off with the money. "It's a secret to everyone, okay? I don't want my wife to find out I haven't quit yet."
That doesn't even begin to explain, however, the shops hidden under trees, bushes, and rocks. That is just a terrible business plan. Those guys are lucky that there's a rampaging elf-boy roaming the countryside setting random fires.
