It’s even funnier when you consider how he must have figured all this out in the first place.
Some folks are asking “well, if he can avoid the no-dry-land curse simply by standing in a bucket, doesn’t that ruin his whole motivation?”, but he’s not on dry land here.
The parley takes place on a sandbar - which, for the unfamiliar, is a temporary “island” of sand deposited by breaking waves, unconnected with the shore, that spends most of its time submerged, being exposed only at low tide.
What Jones is doing here is rules-lawyering his curse. Can you imagine the trial and error he must have gone through in order to determine that this would actually work?
“Okay, do islands count as dry land? How about parts of the shore below the high tide mark? Reefs? Shoals? What if I stand in a pool of water on a shoal? Does it have to be seawater, or will any water do? Does it have to be a natural tidepool, or can it be something artificial, like a bucket?”
What I am saying is that there must have been a process.