Continuity mistake: When the security cameras are shown watching Kleya walk through the hospital, she is walking with a bandaged wounded hand sticking up, and this is shown in most of the camera feeds as well. Except in one shot, she's shown walking with her hands down; then her wounded hand is sticking up once again in the next shot. (00:26:17)
I Have Friends Everywhere - S2-E5
Continuity mistake: When Syril is talking to the Gorman front guys in the alley about the ISB searching his office, the angle of the light on his face changes several times at different angles. Sometimes on the left, then the right of his face. (00:11:43)
Answer: I agree that the aliens' motivation is not clear, and this may all be a writer's shortcut to get Andor and Melshi on to the next part of the story. But I believe they are very disgruntled with the Empire, and I suspect they may be pretending to be more hostile than they really are, just to wind Andor and Melshi up. So - with no other evidence - I think they give up their ship because it messes with the Empire, it helps some mistreated prisoners escape, and the aliens have nothing better to do than walk back to their homes.