Fake news, the AirBnB renter did not have a city permit, they had to leave until a permit could be gained. Not a big deal.
Seth did not leave the laptop for them to find, he did not think he would be murdered, so the laptop was at his home. He was a young idealistic guy, who was probably told by the FBI that they would take care of him and he had nothing to worry about. Then Bam, they shot him.