The 37-year-old spoke out after Cosima De Vito told the Daily Telegraph there were 'rifts' amongst contestants at the time.
She said there "wasn't enough time to bond" with the other contestants because of the immense pressure they were under.
"Maybe because of our strong personalities, we also didn’t get that opportunity. Sometimes it was a misunderstanding because someone took someone else’s song, or some other little things that created rifts between people," she said.
Other contestants on that season included Guy Sebastian, Shannon Noll, Paulini, Rob Mills and Courtney Act.
But Guy says it was Cosima's "competitive" that nature got in the way of her forging friendships.
"I know Cosima struggled with some people but she was highly competitive, and I think that just drove a lot of people [away]," he told 9Honey Celebrity.
He added: "She obviously put the competition side first, whereas there were genuine friendships. Like me and Shannon Noll are mates, and I had a very close mate on the show, Levi [Kereama], who unfortunately passed on -- he was like my little brother. And there were so many others, like Paulini Curuenavuli, who I just got along with so well.
"I just think Cosima can be a little bit negative at times. People like to have a crack at Idol but it changed my life, so I'll never, ever slam it. It was my life source."