 They were less concerned with accuracy and more concerned with shaping the stories to conform with their own personal theological beliefs. With regards to the question of divine inspiration, it's apparent that the authors themselves did not consider these accounts to be inspired, otherwise they would not have tampered with them in such a way. He's speaking about tampering with the accounts and he is absolutely right about that, but the fact is that those accounts are different and that's all you need to know. If they are truly guided by the Holy Spirit, the Holy Spirit is God in Christianity. If you're truly guided by God and you're receiving some sort of revelation, that revelation must of course be identical. You cannot have differences within those two revelations then about the same situation. We're talking about the crucifixion and the words of Jesus are totally different. How can they both then be guided by the Holy Spirit?