According to the following rule, the punt should have been ruled a touchback. The ball appeared to me to cross the plane of the goal. This rule was obtained from the provided link.
"Team A's untouched scrimmage kick strikes the ground in the field of play and breaks the plane of Team B's goal line. While the ball is in the air over the end zone, A81, who is either on the one-yard line or in the end zone, bats the ball into the field of play. RULING: Violation for illegal touching (Rule 6-3-11). Team B may accept the result of the play or next snap the ball at its 20 yard line (Exception rule 8-4-2-b).
http://www.dfoa.com/...l_Rule_Book.pdf