Being an engineer and a DM, I found this story to be wonderful, like the other two Xnab stories. If I was a teacher, I would use the stories and the death traps as physics/engineering lessons, and ask the students on how they would break in, ask them to reverse engineer the traps, and how they might improve upon the traps themselves.
Anyway, there is definitely a line in the story about altering the water pressure:
"The rumor about this place
is that that’s how he rigged the self-destruct. Try to interfere with
the operations and the place comes down on your head.”
Finally, I would point out that Xnab's name should probably be pronounced "ISH-nab" or "ISH-nub" according to a friend with Mayan roots.