Sure. But the proposition was that they had not sinned because they did not know good and evil. To me, it is abundantly clear that had sinned.
To use an analogy.. If people have been driving down a road at 100kmh and one day the local authorities place a 80kmh speed limit sign on the road does that mean the people have broken the law all the times they drove down that road at 100kmh before the 80kmh speed limit was imposed? No.. The new speed limit only governs the people after it is introduced. It only becomes an offense to go at 100kmh After the new speed limit is established..