Larry Niven's "There Is a Tide" (short story, science fiction): Is this exotic world an alien trap?

Another space opera on weird world - humans fighting aliens & winning kind. I am getting rather bored with this kind of stories.

Story summary.

Year is 2830 AD. Louis Gridley Wu, "one hundred and eighty years old", is taking a pleasure trip a bit beyond the fringes of Known Space - alone. And he is always looking for devices called "Slaver stasis box" - sort of vaults holding valuables from long vanished aliens that seem to be scattered around galaxy.

He will spot one that looks like a good candidate near an unnamed planet. He will be challenged by an alien ship that has also just reached there. They will make a deal - both will land on the planet, & toss a coin. Winner takes the booty.

They go down to a beach on the planet's surface. While the coin tossing is going on, alien ship has vanished. Turns out the human was alone but alien wasn't. His friends are going to take the booty anyway. I don't recall how they planned to take the stranded alien - probably by using force against Louis.

So there is this one alien without his ship, & Louis with his ship - on this alien beach. That is when there is a big tide - sea level has gone substantially down near them. What caused it? Planet doesn't have a moon.

Brave deduction, & Louis concludes - the vault they saw above is not a vault but "ten feet of nearly solid neutronium, probably torn loose from a neutron star" (how?), & with "ten million gravities at the surface"; it apparently look similar to valuable stasis boxes. The two run panicky to warn the aliens that have gone to pick up the booty - too late. They will be eaten up by the neutron star.

Human is the kind type. Rigs up an environment for alien on his ship, & promises safe deposition on his planet.

Fact sheet.

"There Is a Tide", short story, review
First published: Galaxy magazine, July 1968.
Rating: B