Bypass snooze if no one is logged on to PC
Currently, if no one is logged in to the PC, a Managed Install with a Snooze will fail. It would be nice if the client UI was just bypassed altogether in this case and the managed install allowed to proceed as if the user either ignored the prompt or selected Install Now. This behavior is what one would typically expect if they chose "Install Now" as the timeout option.
This is what the Install Now/Later setting and the timeout are for. If you set a timeout for 60 minutes and the default action to Install Now, if no action is taken (snooze, install, install later) by a user, the default action is taken after the time out expires.
So, just set your Timeout (on Alert user before run), set the Action to Install Now, and that should accomplish what you're trying to do.