Even if this thing in the ocean is just a lump of heavy metals ejected from some remote cataclysm, that would still be interesting in its own right. Is it really so terrible that he wants to go and look at an actual physical thing from space instead of finishing his career staring at computer screens? Give him a few million dollars and let him have his field trip.
But people don't exactly go running around saying that they're trying to find Thor's spaceship from that time O'Neill, Carter and Teal'c blew it up. (sorry huge Stargate fan) Even if he finds nothing, will the conspiratorial people believe that? Or, will they believe that The Powers That Be hid the Top Secret Alien Technology from the enterprising scientist?
I honestly don't care if he hypes it for laughs, cold hard cash, or because he believes it; as obsessions go this one strikes me as harmless.
You do make a good point about conspiracy types, but I don't think it's necessarily his responsibility to educate everyone out of that. The best way to let the air out of that particular balloon is to send a small rover to the moon and land it near the original Apollo site, and then just drive it around beaming back pictures of stuff on the moon and attractive hi-res pics of Earth on a daily basis.
Does it break any new scientific ground? Nope. Will it do wonders for public awareness of/engagement with science? Hell yes.
Doesn't matter. You just swamp them with volume. The thing about mis/disinformation is that it moves to fill voids, not unlike gas rushing into a vacuum; falsehoods have a first mover advantage because it takes less time to make something up than to report it accurately. But if you're generating interesting content on the regular, conspiracy stuff gets sidelined.
A simpler example again than a rover would just be installing a camera on the Moon that points back at Earth and beaming a high-res whole planet image in real time. The lack of imagination in existing space projects is just deplorable. If you want a bigger science budget, a planetary selfie stick will pay off in spades. Flat earth people will dry up and blow away after a year of people being able to look at the planet they live on and see weather patterns, wildfires etc.
