 Why did the Viceroy blockade the Earth if he wanted an Earthling to come and meet with him?
"If you wanted someone from Earth to come here to see you, why did you put the cordon around Earth? There was even serious discussion of destroying Earth out of hand, while it is still possible. While these creatures could by no means be classed among the intelligent races, there was a general expectation, which we reported to the Sunda, that they would some day come to be numbered among the Servants of the Emperor. Even if you could get down to the bottom of the ocean and tamper with the bomb, you would only succeed in setting it off, and that's what the Sunda had been in favor of in the first place. They provide sixty-eight of the hundred Viceroys; we provide only seventeen.
 The blockade was a test to see if Earthlings were smart enough to help the Vegans defeat the Sundans.
 The blockade was a test to see if Earthlings were smart enough to help the Vegans defeat the Sundans.  The blockade is there to protect Earth from the Sundans.  The blockade is there to quarantine the Earth. Earthlings may have diseases that could infect the other races.  The blockade is there to keep people from leaving the Earth.