During the long flight, Sheyan did not remain idle. He asked some questions he wished to know, such as how to pilot a large Imperial spacecraft, and things to look out for in a long voyage.
The Lieutenant apparently knew that Sheyan was a VIP guest, and he had also heard of Sheyan's feat of flying a Wasp to Uplos and back, so he answered every question he could.
Sheyan asked these questions for a reason. Before he departed, he had already learned from the Realm that there were often turbulent dimensional rifts in places where the primary plane overlapped with other subplanes.
That means astonishing acceleration and wild maneuvers. As far as the physique of the pilots in the Empire were concerned, they already found it difficult to get through the asteroid belts outside Uplos, let alone traveling through a dimensional rift. That means Sheyan must go alone, and he naturally had to pilot the spacecraft himself.