What were non-Peacekeeper Sebaceans doing on a ship?

"Captain D'Argo. Our ship is called Moya."

Captain Archer turned to the woman on his left. "Can you translate that?"

Why didn't they have translator microbes? "Maybe you should speak to them," he said to Aeryn.

The two people on the screen immediately stopped talking and looked at him. "You speak English?"

"Er, yeah. You're human?" What were humans doing outside of the solar system?

"Yes. We thought we were the furthest humans from Earth."

Seemed like they both had a story to tell.