When I first saw this I immediately said that the official blew it. Casually walking the ball within the endzone definitely indicates that no attempt is being made to advance the ball out of the endzone. This is particularly obvious when many of the opposing team arrive in the endzone. Poor play by the returner; terrible refereeing by the official.
I disagree. The official has to enforce the rules as written, not some interpretation of the player's action. For all the official knows, it could have been a trick play by Wofford akin to all the high school/pee wee "Hey coach, this is the wrong ball... Now I'm running for a touchdown!" plays you can find on YouTube. Lull the coverage team into a false sense of security, then flip a lateral and try to go for a touchdown.