but the option to choose a new time was greyed out
Which only ever happened for me if I had already pushed back an update multiple times. Which then means they had all the time in the world to make sure they do the update before they start such a critical, multiple days long process. These are people without forced update they would never make updates and they are the reason forced updates have to happen now.
Plenty of reports to the contrary
https://www.reddit.com/r/Windows10/comments/47biyb/windows_10_restarted_while_i_was_in_the_middle_of/
From your link:
Which only ever happened for me if I had already pushed back an update multiple times. Which then means they had all the time in the world to make sure they do the update before they start such a critical, multiple days long process. These are people without forced update they would never make updates and they are the reason forced updates have to happen now.