Speaking to Digital Spy and other journalists, O'Leary accepted that while complaints about Maloney being "dated and cheesy" were not "inaccurate", he respects the Liverpudlian for knowing the kind of artist he is.
"It's always really important for the show to evolve and move on," he said. "So when you get a contestant like Christopher this year... my heart soars, because you know they're coming to the show with something.
"I think when we first started you saw people turn up and say to Simon Cowell, 'You tell me who you want to be', and we don't get that anymore... now we've got people who have an idea about their own marketing, and how they see a proper career path. That for me is a good thing."
Flack, who presents companion show The Xtra Factor, added that Maloney is only performing "songs that he wants to sing, songs that he likes singing".
O'Leary continued: "I don't necessarily think it's inaccurate [that people say he's dated]... He makes no apology about it and fair play to him.
"I'm thrilled he's got to the final, because he's got to the final singing songs that you probably wouldn't normally sing on X Factor.
"You can go on about him being dated and cheesy as much as you like, but at the end of the day he's not pretending to be anything he's not. I quite like that about him."
Asked who they are backing to win The X Factor, O'Leary teased that his "favourites have changed throughout the show", while Flack said she is happy with all three finalists.
"[In] these three final contestants there's something for everyone," she argued. "You've got James Arthur for your cool kids, Chris Maloney for your mums and your nans and then Jahmene Douglas for everyone else."
Maloney has told Digital Spy that the music he wants to release after The X Factor will "surprise" viewers.