No, stop, seriously, no, stop stop stop.
That series is not a good model for a healthy, consensual, supportive BDSM/impact play relationship.
the idea that someone is teaching a disregard for safe words, especially in a book with such popularity, terrifies/disgusts me. Safe words are such a huge, important tool, but in order to be used as such THEY MUST BE USED CORRECTLY. I don’t just mean in BDSM play, though that is the community from which I learned of the concept, I think it is helpful for all manner of situations. It’s handy to have a time out that is immediately acknowledged and respected. It’s made me braver and bolder about trying all manner of things, from boxing, sparring and wrestling to general horse play and tomfoolery with those whose size might otherwise intimidate me. As a person with an explosive temperament I will often use it in an argument, and having the instant timeout when I begin reaching a point of blowing up has saved me a lot of trouble.