Clarence Thomas Defends Undisclosed Trips. Here Are the Facts. — ProPublica

"It is absolutely impossible that anyone could reasonably interpret that exception to apply to private jet flights," said Walter Shaub, former director of the U.S. Office of Government Ethics. "Not in any universe." 

Richard Painter, who served as the chief ethics lawyer for the George W. Bush White House, said Thomas' explanation of why he didn't disclose the trips "makes absolutely no sense." Painter emphasized that the exemption only covers three categories: food, lodging and entertainment. Private jet flights would fall into none of those, he said...

https://www.propublica.org/article/clarence-thomas-response-trips-legal-experts-harlan-crow