Enlarge (credit: Getty Images | Carol Yepes) Elon Musk has cast more doubt on his willingness to buy Twitter, criticizing the company's CEO and saying the "deal cannot move forward" until Twitter provides data behind its estimate of spam accounts. Musk also said this week that renegotiating the deal at a lower price is "not out of the question." Musk says he thinks at least 20 percent of Twitter accounts are fake or spam, while Twitter said in a Securities and Exchange Commission filing that fewer than 5 percent of monetizable daily active users (mDAUs) are spam or fake.