First off, the joke was hilarious, and it was hilarious because its true. It riffs off of very real conservative initiatives in recent years like warmongering and torturing. And it doesn't take a "radical liberal" to either see these facts or find jokes about them funny.
But what's really telling here is the claim that by not telling jokes like this, we could reduce flame wars. What that really amounts to is a kind of threat, "if you guys make fun of us conservatives, then we're going to start flame wars! Wouldn't it be better if we all just kept quiet and pretended that the rampant flaws in the conservative ideology weren't there?" Which is typical of conservatives, using threats to try and squelch speech, ideas and facts.