Did he actually say private practice? Or did he say to practice law? Potentially two different things.
"Whatever skills I may have are better utilized in a courtroom than in Congress, and I enjoy our justice system more than our political system," the South Carolina Republican said.
And in a sign of Gowdy’s desire to step back from public life, he recently turned down a golden opportunity to become a federal judge."
https://www.politico.com/story/2018/01/31/gowdy-wont-seek-reelection-380231