 Why does Loy Chuk build an artificial environment for Ned?
A scream of brakes, the splash into icy waters, a long descent into alkaline depths ... His car hit the white-painted wooden rail sideways, crashed through, tumbled down a steep slope, struck a huge boulder, bounced up a little, and arced outward, falling as gracefully as a swan-diver toward the inky waters of the Pit, fifty feet beneath.... The icy breeze tore tiny puffs of dust from grotesque, angling drifts of soil, nearly waterless for eons. Loy Chuk had flown his geological expedition out from the far lowlands to the east, out from the city of Kar-Rah. He could think and dream and invent, and the civilization of his kind was already far beyond that of the ancient Twentieth Century. Loy Chuk and his fellow workers were gathered, tense and gleeful, around the things their digging had exposed to the daylight. The dry mud that had encased it like an airtight coffin, had by now been chipped away by the tiny investigators; but soiled clothing still clung to it, after perhaps a million years. A perfect preservative for organic tissue, aided probably during most of those passing eras by desert dryness. The final instrument he used to test the mummy, looked like a miniature stereoscope, with complicated details. Medical and biological sciences were far advanced among Loy Chuk's kind. It might move, speak, remember its past! With infinite care it was crated in a metal case, and hauled into the flying machine.
 He needs a habitat for Ned, so he can study Ned in a natural setting.
 He needs to keep Ned calm. If Ned believes himself to back in his own time, he will remain calm.  He realizes Ned is mentally unstable from the trauma of being brought back to life. He doesn't want Ned to commit suicide.  He needs a habitat for Ned until they can figure out time travel.  He needs a habitat for Ned, so he can study Ned in a natural setting.