K9, sent to investgate by Tellac's president, discovered that Votri and his fellow miners wished to remain "missing". They had discoverd Star Crystal on the planet and did not want their rapaciously greedy company to find out about it. Since it allowed the free movement of people between universes, they feared that Tellac would use it merely for profit, bleeding each and every parallel universe dry.
Atrios therefore conspired with K9 to keep their presence a secret. K9 agreed, allowing Atrios to continue to use the Star Crystal without interference from others. Atrios somehow knew of the Time Lords, and he enjoined K9 from telling even them about the Star Crystal. K9 complied when he submitted a somewhat vague report to the Time Lords. (PROSE: K9 and the Missing Planet)