Disclosures from a former Twitter Inc executive turned whistleblower show that at least one Chinese agent is working at the company, Senator Chuck Grassley said in his opening remarks during a Senate hearing on Tuesday featuring testimony from the whistleblower.Peiter “Mudge” Zatko, a famed hacker who served as Twitter’s head of security until his firing last year, said during the hearing that some Twitter employees were concerned that the Chinese government would be able to collect data on the company’s users.He referenced a Reuters story on Tuesday that detailed internal clashes between some teams that wanted to maximize the ad...