WASHINGTON — A former security chief at Twitter told Congress on Tuesday that the social platform is plagued by weak cyber defenses, privacy threats and the inability to control millions of fake accounts. Peiter “Mudge” Zatko, a respected cybersecurity expert, appeared before the Senate Judiciary Committee to lay out his allegations.“Twitter’s misleading the public, lawmakers” and regulators, Zatko said as he began his sworn testimony.“They don’t know what data they have …