The spirit of the rule is to keep the memes community from being a place for proselytizing one's politics.

So, for example, using a >50 year old event in a meme to show "this is why communism is bad" or "It's like we're all on the Titanic, because we've gotta watch out for ICE!" would both be rule-breaking, but something like "local man named Abe Lincoln refuses to go to theater" would be fair game.