If you do a search on the internet, you’ll find that this era of the VQ engine had issues with burning oil. If you allow the oil to get low, you’ll start to have issues with the timing chain. Nissan made revisions to the engine in 2006.
He can contact Nissan about paying for the repair. He should have all his maintenance receipts to show proof he kept up on maintenance. My guess is he will be even more frustrated after talking to Nissan. His best bet is to find an independent garage to make the repairs. Lots of independent mechanics have experience working on these engines.