Mainline conservatives generally miss the point of moral relativism. It's not just (as Rush says) to normalize folks who would otherwise feel abnormal. That's a nice unintended side effect, which holds the loyalty of the already orthodox.
As always, look to Orwell for the real point. In his essays explaining "1984", Orwell maps out the leftist method, and it has been refined considerably since then. You start by locking the target into Room 101, where he is put face-to-face with his worst fears. With poor Winston Smith, it was a cage full of hungry rats placed against his face. (For me, it would be ANTS, no doubt about it!) With modern conservatives, it's a cage full of kinky sex.
For extra spice, modern Orwellians mix in several gallons of cognitive dissonance, usually known as outing
or hypocrisy detection
If you can get the target to think "I hate this / I am this" simultaneously, you're well on the way to victory. Cognitive dissonance, simmered in a sauce of relativism, leads the mind into a flashing state of total confusion and ultimately to burnout. At that point the target has a
razed consciousness, and is ready to be retrained (Brocked).
So the ultimate purpose is not "Anything goes." That's just the first stage, which may be enough when dealing with younger folks who have already supplied their own dissonance by natural rebellion against parental authority. After the independent mind is tenderized, it can be re-crystallized with the Party's own moral code. That's the goal. Not just to believe that 2 + 2 = 5, but to believe that
2 + 2 = [Whatever the Party says it is RIGHT NOW],
and then to generate your own slogans and reasons for believing this.