Just curious, was it a carbon seatpost? I can imagine the twisting method on steel, but carbon is less forgiving. I've added the liquid wrench and attempted to twist a bit some time later. No budging. I suspect the carbon is starting to crack from twisting.
At this rate, it seems like the seatpost is a goner. I'll likely saw it off and try to saw it out. Then replace it with a cheap aluminum post.