That explanation does not hold water.
First of all, there has been no suspense during the entire run of this show. Build-up to the finale? Everyone knows AJ or Chantel will get in next week. In AI2 it was obvious by the second week that it was a two-man contest between Clay & Ruben.
As far as keeping the results confidential, they could just show the vote totals on the results show AFTER everyone has voted. They already announce to the world which three kids got the most votes. I'm sure being one of the kids who got the least votes every single week isn't too much fun either.
Keeping the results secret on AI makes even less sense since everyone knows who got the least votes who was in the bottom three. Also, being the lone person voted off can't be a real thrill.
If they showed vote totals it may spur fans on to vote even more for their favorites.
Sorry, they can explain all they want. They haven't come up with any reasonable explanation for hiding the results.