This was mentioned on another ballroom board I read, but if you read the rules on the ABC site, you'll see that the fans' vote was all that really mattered in the final round. It first talks about the general scoring, 50% judges, 50% fans, and how 1st to Xth place gets X to 1 points. After that it says that if there's a tie, the fans' vote is the tie breaker. If by some miracle, the fans' vote is tied, then Len as the head judge would make the decision.
The final round only had two couples, so there were only two basic outcomes -- the judges and fans agreed on who the winner was or they didn't. If they agreed, it was over. If they didn't, it would be a tie and the fans would get the tiebreaker vote. So in effect, the judges' final round votes meant nothing. Assuming everything was fair, Kelly had to have won the public vote because if she didn't, John would have won the championship. But you're right, it would have been nice if they had revealed the results of the public vote all along.