By Hyunjoo Jin (Reuters) -The U.S. securities regulator quizzed Elon Musk last month over a tweet in which the world’s richest person raised doubts over whether he would move ahead with his $44 billion acquisition of Twitter Inc due to concerns over the number of fake users on the platform. The U.S. Securities and Exchange Commission (SEC) asked Musk in a letter whether he should have amended his public filing to reflect his intention to suspend or abandon the deal, according to the June 2 letter made public on Thursday. The agency was referring to his May 17 tweet in which he said the “deal c…