Just the evidence of high vertical G loads indicating it hit fairly flat on it's fuselage by itself doesn't mean it was in a flat spin. The Amsterdam recent incident crashed much like that landing flat but with a high sink rate. If they were in a spiral dive and saw the ocean coming towards them in the final seconds they would attempt to pull out wings level but if they couldn't they might hit flat or even nose up with a very high sink rate at impact. I hope somebody finds the black boxes to find out exactly what happened.