I feel like this article mischaracterizes sysinternals as something of a Microsoft critic and watchdog which just wasn't the case. They were more like a valued and vital member of the Microsoft ecosystem.
If you did development on a Windows machine in the last 20 years, you probably downloaded a sysinternals tool at one point. Many Microsoft KB articles pointed to their tools and articles and when Microsoft announced their acquisition, most people were like "That makes sense".
I completely agree but I can at least image where the critic characterization comes from. Mark's articles and the Sysinternals tools gave us wonderful insight many parts of Windows. They showed the good things but often times they also pointed out the flaws.
I think Mark is just honest about the technical aspects of Windows and thankfully his attitude has not changed since Microsoft pays his checks.
One example of this are his videos about Windows Memory Memory management (from 2011, hosted on MSDN)[1], which besides being a detailed technical explanation don't skip all the shortcomings of Windows' memory subsytem. Sometimes his statements seem harsh but I think it's more sincerity and he has been as sincere about his own tools as well[2].
I too had always felt that sysinternals was a champion of Microsoft and Windows. Perhaps there were some politics going on that only Microsoft employees would know?
Every system has pros and cons and learning how to work with those constraints is how you become a master. From what I understood Mark is one of a small number of people who has an extremely deep understanding of Windows inner workings.
If you did development on a Windows machine in the last 20 years, you probably downloaded a sysinternals tool at one point. Many Microsoft KB articles pointed to their tools and articles and when Microsoft announced their acquisition, most people were like "That makes sense".