Could be an awkward situation. If Fenn refuses to disclose where the treasure was buried, he'll go down as one of history's biggest douchebags, at least in the minds of the many people he inspired to search for it.

If he does disclose a location, and the treasure never actually existed, then he risks someone calling BS. ("I searched in that exact spot last summer and here's the GPS history on my phone to prove it.") He would also have to make his way out to the stated location at the spry young age of 89 and dig a plausible-looking hole.

So people are really going to resent him unless the treasure was real and he discloses where it was. It's understandable if the finder remains anonymous, but the burial location had better not.