This seems like a pure depth move to eat up some innings in the minor leagues. It seems very doubtful that Figueroa would ever be called up to the Bronx unless there is an emergency situation. Even then, the Yankees have other options more appealing that Figueroa. Sometimes somebody has to pitch.
Figueroa turns 38 next month and has a career 4.55 ERA in 499 career Major League innings. In 29 innings with the Astros last season he had a 8.69 ERA.