I got bitten by this last week and again today. I had previously configured Windows 10 Pro's custom restart time such that my machine would not restart until x days later at a specific time if there were pending updates.
I've always kept on top of this every day and check each day to see if there are any pending updates and have always installed these updates within 12-24hrs of them appearing, or nudging back the restart time by a day or so if it's not been convenient. This approach has worked fine for months....until just recently.
In a recent update the "Use a custom restart time" feature has been disabled and all I can do now is specify my "Active Hours".
I even had the Local GP setting you suggested configured as well.....but Windows 10 really needed to reboot my PC, ignoring my "Active Hours" and any and all of the Local GP settings you can throw at it. Twice in the past seven days I've been given the 20 minute warning and there is damn all you can do about it....despite all of these workarounds and overrides.
In all fairness I think the author of the article has probably just had it up to the back teeth with Windows 10 and the seemingly new ways it finds to totally fuck up your working day. I've been a MS developer for 20 years, I really like Windows 10 but I've gotten pretty close to the author's levels of exasperation myself over the past few days with some of its control freakery.