Yup - should have said that the down will absorb some of this moisture, not all of it. (some of that moisture comes from your breath, which doesn't hit the sleeping bag) Did not mean that the entire 1.5L would end up in the bag as you mentioned (Yikes). But over multiple days in cold or humid conditions, a down bag could very well look like a pancake. I assume this is why many expeditions into high altitude, cold conditions will employ high loft synthetic bags over down.

I was not speaking about winter hiking; 3 season for some of us means facing a lot of moisture during these months - i.e. 12K feet in the Rockies.