He can pilot it himself. I think if you are going to have a mega yacht, sail is the way to go over power. Yeah, it's a floating home, but it can also sail - that's awesome. You can take a tender into harbors.
Also, longer sail boats can go faster than smaller ones, when you don't plane. So a bigger boat means you can travel faster over long distances.
He can take the helm or push some buttons to trim the sails when they're on open water, but I doubt Perkins is the guy navigating harbors and docking it. With a yacht that big it takes a professional. Their crew is 20 people!
And while I've certainly never been on the Maltese Falcon, with a boat that big it seems like there wouldn't be much difference between a motor yacht and sailing yacht, except the sailboat heals over a bit and you save a lot on fuel.
Also, longer sail boats can go faster than smaller ones, when you don't plane. So a bigger boat means you can travel faster over long distances.