question:  Why were the Sirian spiders rejected for the travel plan?
context: My three staff men, Auchinleck, Stebbins and Ludlow, walked shieldwise in front of me. The aliens came in every shape and form, in all colors and textures—and all of them eager for a Corrigan contract. I thought of it privately as MacTavish IV and referred to it publicly as Ghryne. We had saturated MacTavish IV with our promotional poop for a month preceding arrival. His last visit to the Caledonia Cluster until 2937, so don't miss your chance! "I'll be placed on exhibition at your Institute on Earth. I'll be required to remain on exhibit no more than one-third of each Terran sidereal day." We needed a green Regulan in our show; the last one had quit four years ago. But just because we needed him didn't mean we had to be extravagant in hiring him. The next applicant was a beefy ursinoid from Aldebaran IX. He was followed by a roly-poly blue-skinned humanoid from Donovan's Planet, four feet high and five hundred pounds heavy. I passed him along to Auchinleck to sign at anything short of top rate. If there's any species we have a real over-supply of, it's those silver-colored spiders, but this seedy specimen gave it a try anyway. It was the isolationism of the late 29th century that turned me into the successful proprietor of Corrigan's Institute, after some years as an impoverished carnival man in the Betelgeuse system. Back in 2903, the World Congress declared Terra off-bounds for non-terrestrial beings, as an offshoot of the Terra for Terrans movement. Before then, anyone could visit Earth. After the gate clanged down, a non-terrestrial could only get onto Sol III as a specimen in a scientific collection—in short, as an exhibit in a zoo. At the same time, we had turned away a dozen ursinoids, fifty of the reptilian natives of Ghryne, seven Sirian spiders, and no less than nineteen chlorine-breathing Procyonites wearing gas masks. The demand for beings from Wazzenazz XIII is pretty low these days.
output:  They had an over-supply of their species.
options:  They demanded too high of payment.  They had an over-supply of their species.  They all expected a handout  They were difficult to work with.