This story was from a Sci Fi TV episode in the 1980's or 90's, but I cannot remember exactly when or from where.
A man is awaken from suspended animation to a post-apocalyptic society facing an inbound asteroid threatening the world. He was awakened by the leaders of this world because he has knowledge of a long past space defense system (still in orbit) that could destroy the inbound asteroid and is asked to help them.
The man learns that the new society has emerged from a post-nuclear war and has resorted to an environmental friendly technology shunning the pasts use of destructive technology; the new environmental technology includes embryonic animals who "choose" to become computer-like intelligence. One of these embryonic computers shows the man the inbound asteroid.
Anyway, when the time comes to destroy the asteroid, the man activates the relic defense system, but telemetry data of the asteroid shows its slowing down and is taking an orbital path around Earth.
The man is dismayed to realize the asteroid is a space ship and that the embryonic computers concealed this fact from him so that he would destroy what is actually a ship from his past. He watches in horror as the orbital defense system activates on the ship obliterating it before it could land (once activated it could not be stopped).
The new leaders explains to him that the ship had people from his past who originally were responsible for the nuclear holocaust, and who had escaped its devastation by leaving Earth on a ship traveling at relativistic speeds. It had politicians, military generals, top CEO's and other elitists on board. It even had nuclear weapons with them, and the new leaders were fearful had they landed it would end their new society.
The story ends with the man feeling remorseful that humans never ascended the stars but the embryonic computers shows him this new society actually had explored the many wonders of the universe he thought were unreachable.
This was an episode featured on a show like "Amazing Stories," but I could not find a match to the plot description. Anyone have any idea on what show this story had appeared in?