 Why was the Vegan not chosen to make the trip to Earth?
The aliens came in every shape and form, in all colors and textures—and all of them eager for a Corrigan contract. 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. He was followed by a roly-poly blue-skinned humanoid from Donovan's Planet, four feet high and five hundred pounds heavy. 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. 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.
 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.