I'm thinking about this from a programming prospective here. It's not a bug in my eyes, this appears to be something working as intended.
The task that controls Windows Update is waking the computer - exactly as it has been told to do inside of task scheduler. Whilst this feature may not be desirable, IMO it's not a bug.
If you could produce a list of steps that should produce one outcome and produces another, then we're looking at a bug. For example, when clicking the properties button on a VPN's IPv4 setting the properties dialogue should appear. In Windows 10, this window does not appear. This is a bug since an intended feature is not working as it is meant to (and this is an actual bug in W10 that is really irritating me!)
(I welcome alternative views [but don't want to argue] on this - just my opinion)