1. Letting some one know when they have done something well or in a way that gives you joy isn't necessarily controlling or placing conditions on love. That is a huge leap, and isn't proven.
2. Sometimes we do need to control kids, and to teach them to control themselves. And part of that is telling them when they are doing the right things, which is praise.
It's lovely to think that if we just gentle talk to kids and explain why certain behaviors are acceptable and other aren't, they will get it and comply to an extent that society can live with, and for some kids, its true. However, other kids need a lot more than that. If your kid went to school with a kid who needed a lot more than that to really get they it isn't OK to punch your kid in the stomach whenever the teacher isn't looking, would you really still be against praise and behaviorism, or would your beliefs go in the trash if it meant that your child was safe from being a punching bag?
Assume in your answer that just kicking the kid out isn't an option -- that you have to figure out a way to help the child learn socially appropriate behavior, because that is real life. The kid needs to be controlled. We, as a society, don't get to throw the kids away who aren't as easily socialized as Kohn would prefer they be. We have to teach them better, and hopefully do it before they seriously hurt another person.
Behaviorism isn't discredited, and it is widely used to with children who have proven resistant to softer approaches, such as children with certain types of special needs or behavior problems. It wasn't the top choice for me with my kids, but it has a place. Kohn looked at a lot of research, but he has never spent much time around children. If he had, he would realize that part of the reason adults have an obligation to control children is to keep them from hurting each other, or growing into the kids of adults who have to be kept locked up.