What version of Windows 10 (as in Home, Pro, etc.) are you using and what version number?
The control over Restarts for updates can be made pretty tight even on Home, but even tighter on Pro. The fact of the matter is that you cannot put off updates themselves or restarts "forever." You can set the system to give you notification that a restart is needed or scheduled and to defer it up to three times, but if you keep deferring it after time three it will restart.
This is why I encourage people to check Windows Update settings manually before they kick off something that is critical that would run during what are normally inactive hours. That way you can choose to restart yourself, before inactive hours start, and avoid the problem entirely.
I know of no way to make the restart process in response to updates that require one entirely manual. That was most likely taken away because it was so common for so many to refuse to apply updates, period, and this has been retrofitted in Windows Update back to Windows 7 when I last read anything about it.
You could also choose to make your "inactive hours" during the working day and ask for notification prior to restart. That gives you a lot more control over the process.
Edited by britechguy, 11 January 2018 - 10:06 AM.
Brian AKA Bri the Tech Guy (website in my user profile) - Windows 10 Home, 64-Bit, Version 1809, Build 17763
Presenting the willfully ignorant with facts is the very definition of casting pearls before swine.
~ Brian Vogel