 Why are the peace talks on Saarkkad V?
Somewhere out there, the ships of Earth were ranged against the ships of the alien Karna in the most important war that Mankind had yet fought. He was not in the battle line, nor even in the major production line, but it was necessary to keep the drug supply lines flowing from Saarkkad, and that meant keeping on good terms with the Saarkkadic government. To violate the rigid social setup of Saarkkad would mean the instant closing off of the supply of biochemical products that the Saarkkadic laboratories produced from native plants and animals—products that were vitally necessary to Earth's war, and which could be duplicated nowhere else in the known universe. Not the worst ones, of course; there were places in the galaxy that were less important than Saarkkad to the war effort.
 The Karna consider Saarkkad V to be neutral territory.
 Saarkkad V is not inhabited by intelligent life.  The Karna consider Saarkkad V to be neutral territory.  The inhabitants of Saarkkad V don't pose a danger to the Karna or to the humans.  Saarkkad V is halfway between Earth and Karn.