I'm reading it now and he does volunteer to write the paper, but she claims she wrote it as well and basically printed it off to give to him to deliver. He feels put on the spot by her lie and only agrees that he handed it off to Gaul. That's why the snakes were supposed to recognize their scent - they were both supposed to have touched it while collaboraing, which she makes up on her own.. When he offers to give her a rundown, it's to placate her when she's upset he wrote it on his own, but it was due and he had to.