All those answers recognize that its a trick though!

Indeed, but, no LLM has ever realized that I don't actually specify that he can only take one thing at a time. It's natural that it would assume that (as would most humans) because it would be so heavily primed to fill that in from every other version of the puzzle it's seen.

I'd give them full credit if they noticed that, but I was also wanting to see if, given the unstated assumptions (one thing in the boat, don't let anything eat anything else, etc) they'd realize it was unsolvable.

most humans would not assume that since most humans are not heavily primed by logic puzzles.

Why is it unsolvable? I am confused.

The unstated assumptions, common in all the other puzzles of the kind, are that the farmer wants to bring everything across, nothing is to be eaten by anything else, everything must be brought over by boat, and the farmer can only bring one thing in the boat at a time. Anything left with something that will eat another thing will eat it.

This variation of the classic puzzle is unsolvable. If you have a solution, let me know.