And yet there are 100% single player games that require a phone-home server to be active.
If Astro Bot doesn't do that, then it's irrelevant if you have it on a disk, or if you have a digital download. Assuming, of course, the digital download remains available, you get the exact same functionality.
And, likewise, regardless if you have the game on a disk or from DD, if it requires a server somewhere to be online, you do not have any control over the game or when you can play it, because it can always be rendered unplayable by the publisher pulling the plug on the server.