No matter what the news, there's going to be bullish spin on it. If GDP were up, that would be a reason to rally because that means the economy is growing (it wouldn't matter if it were growing too slowly for employment to keep up with population growth, because growth is growth). Since it didn't just miss expectations, it's actually DOWN, well, that means more quantitative easing for a long time, so that's bullish.
Who cares if we're slipping back into recession (even on paper, never mind the fact that there never was a real recovery to begin with)? It's FREE MONEY FOREVER!