Dropbox suits him just fine because it is easier to understand. Just install the app and wait. Files are synced automatically. He does not have to be online at the same moment as his relatives. And any future shares would also be synced automatically. No need to create a fresh torrent file. And shares would be synced on both sides. So both the parties can easily share stuff with each other. Cannot get any simpler than that. I recommend Dropbox to anyone with uncles and aunts who are not comfortable with computers.