It wasn't the cult that made it relax, in fact Reaper concluded that the Archdragon had likely been forgotten about. What made it relax was that it could now use its archived maps of home and fill in points. And it now had a rough path of how to get to the draenei, or more accurately E'Lune. Ve'len needed a jump start, and E'Lune and Huntress were the only two it knew of friendly enough to offer, and it had no idea where Huntress was hiding. Now that it had a path, it headed toward the town with the cult, avoiding the sensor outposts entirely, since it had gotten the information it needed. Unless it was a trap, of course.