Many people have a misunderstanding of what the Stop Killing Games movement is about. It's about trying to get governments to pass a law that requires game developers to have a plan in place for when they shut down the servers of online games. In the current gaming landscape, games can be taken offline at any moment for any reason. And when that happens, you're shit out of luck. The Stop Killing Games movement believes that if/when this happens, the publisher needs to have a plan in place to ensure that those games can continue to be played. This can take on many forms: modifying the game to not require an online connection, or releasing the server binaries so that players can host their own custom servers, or something of that nature. Worst comes worst, if none of this is possible, then the movement demands that it's made clear in the game's advertisement that you could lose game functionality when the servers shut down. Essentially, the laws surrounding game licenses are vague, and the movement wants a clarification on what buyers are entitled to when they buy a game.
The primary reason why many people have a misunderstanding of the movement is because a large YouTuber named PirateSoftware made 2 videos where he outright lied about what the movement was about and trashed it. He also made multiple statements on his streams where he purportedly "disproved" the movement, where he continued to lie about the movement and trashed it. His videos and statements were the most commonly viewed coverage on the movement, and this disinformation supposedly severely hampered the momentum of the movement, such that even now, many people still believe that the movement is about forcing publishers to keep their servers online indefinitely (it's not).
PirateSoftware was a former developer at Blizzard and was making an online game at the time, so some people speculate that the reason he lied about the movement was because he had a vested interest in keeping the current vagueness of the laws. As more and more people attempted to call him out on his disinformation, he doubled down and refused to admit that he gave any sort of incorrect information, even when the information is provably incorrect.
Apparently, PirateSoftware has a history of this sort of behavior and has gotten himself into some previous scandals due to his seeming inability to admit that he was wrong at all. This has led otherwise minor, forgettable mistakes to balloon into giant controversies.
Taken together with this recent controversy with Stop Killing Games, his reputation has taken a significant nosedive and many people now believe that he's a narcissist who is willing to take down the movement for the sole purpose that he wants to be seen as the smartest guy in the room.