 Why was the Vegan not chosen to make the trip to Earth?
It was our first day of recruiting on the planet, and the alien life-forms had lined up for hundreds of feet back from my rented office. The aliens came in every shape and form, in all colors and textures—and all of them eager for a Corrigan contract. If you are a non-terrestrial, there may be a place for you in the Corrigan Institute of Morphological Science. His last visit to the Caledonia Cluster until 2937, so don't miss your chance! It's the best of its kind, the only really decent place where Earthmen can get a gander at the other species of the universe. 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. A Terraphile alien who goes to the extent of rechristening himself with a Terran monicker would work for nothing, or even pay us, just so long as we let him get to Earth. The next applicant was a beefy ursinoid from Aldebaran IX. Our outfit has all the ursinoids it needs or is likely to need in the next few decades, and so I got rid of him in a couple of minutes. He was followed by a roly-poly blue-skinned humanoid from Donovan's Planet, four feet high and five hundred pounds heavy. 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. Every alien wants to see Earth once in his lifetime, and there's only one way he can do it. 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. It was also my sad duty to nix a Vegan who was negotiating through a Ghrynian agent. So we had to do without the Vegan. I had turned away three more ursinoids, hired a vegetable from Miazan, and said no to a scaly pseudo-armadillo from one of the Delta Worlds.
 The upkeep for the species was too much.
 There were too many of his kind already in inventory.  They were worrisome and difficult to work with.  He was much to large in size to accommodate.  The upkeep for the species was too much.