Let me say, The Simpsons managed same idea better. I am not saying that same ideas cannot be reused, just this episode had no logic.
Ok, this couple find a civilization in an Ice Age. It is explanatory as it is situated in a freezer. But were does soil and trees everything else comes from if there is just ice. Well ok. I suppose I have to just take it as it is.
Then the end ruins everything. If Freezer evolution is similar to Earth evolution then the finale does not make sence.