The man who shot and killed one of the most wanted terrorists in U.S. history is contesting allegations that he refused to wear a mask while aboard a Delta Air Lines flight that he was kicked off of on Thursday.

Robert O’Neill, who is best known for killing al Qaeda leader Osama bin Laden, had shared a tweet of himself sitting on a Delta flight sans mask on Thursday morning with a caption that read, “I’m not a p—y.” O’Neill pulled the tweet down after users criticized him for the content, which included a man wearing a mask and a U.S. Marines Corps hat in the background.