Oh, find out when he gets back, hm? So Kadaj had no intention of sticking around to face the consequences. He was going to tell the people that mattered and abscond, leaving Nnoitra to take the heat.

"You gonna go an' inform Kuja personally, or let him find out from Illua?"

Either way would be fine. The latter would probably be more sensible given how Kuja was one of the only people with the ability to make Kadaj feel guilt. The longer Kadaj stayed in the Palace, the more chance he had of The Sound Five finding out what he'd done and taking matters into their own hands.

Nnoitra could handle them if they came for him. Probably.