Clark claimed the affair on ABC News' "Prime Time Live."
"It's a shocker that I think a lot of us have been hearing about for the past week, preparing ourselves for," Aiken said in an interview on "The Early Show" Thursday morning. "Last night kind of threw a lot of curveballs our way."
Aiken, Clark and other contestants lived together in the Idol House during the 2003 season. He said that they could not leave the house without checking in and out.
Aiken called Abdul a "nurturing and caring person" who gave contestants support and advice.
"She was like that for everybody on the show," he said.
Aiken also suggested that much of the evidence for the supposed affair was either circumstantial or came from Clark's family and close friends.
DISCUSS AND COMMENT ON THIS STORY Reality TV World now offers Facebook Comments on our stories. To post a comment, log into Facebook and then 'Add' your comment. To report spam or abuse, click the 'X' in the upper right corner of the comment box.