If it helps, I (Mike) don't know who @stmw is. I can at least say they aren't one of the four authors of this book.

That said, I don't think the reasonable conclusion to come to when someone is supportive of a product is that they are invested in it. Sure, suspicion is a healthy thing, but for the record you can look through my comment history and see I recommend LeetCode and a coding book called EPI. No compromising connections—I just like the products and let people know about them when I see people talking about the topics. ¯\_(ツ)_/¯