Unless a user is currently on your friends list, we only know online/offline states when registered via [`BeginWatchingUserPresence()`](https://github.com/ppy/osu-server-spectator/blob/0ed0a1f57fbefea6e4e39dbee7c30475e3594a25/osu.Server.Spectator/Hubs/Metadata/MetadataHub.cs#L114).