Some societies even refuse to tell their populations about time travel, supposedly in the name of emotional health, but possibly so that their leaders, who most likely were close to the Zerg imposters before they fled or were captured, can maintain their control. These are some of the least technically advanced societies, as well. Times whose populations have fled, or were killed should most likely not accept instructions or data from such places and times.
See:
Alien Invaders Are In Violation Of Existing Laws
Time Travelers Are In Violation Of Existing Laws
Freedom of Information Act - A Law In The United States of America
Ignorance Of Fact Or Law Is Not A Valid Legal Defense
Criminals Occupying Bodies Or Identities Vacated Because Of Attacks
Criminals Disguised As Or Impersonating Friends To Seem Trustworthy