I agree that the PMBOK talks about implementing the Risk Response Plan in Monitoring and Controlling process. If you read further it talks about executing the risk response plans during the "LIFE CYCLE" of the project. Bottom line is during the monitoring and controlling risks, we will be monitoring the risks and based on the findings/triggers etc it may lead towards implementing the risk response plans but it does not mean the response plans have to be implemented or executed during the monitoring and controlling process. My 2 cents worth when you are reading the PMBOK please give importance to each line as you are doing but revisit/review your understanding from the overall perspective. I would answer "NO" for the question "Implementation of risk response plans done in Monitoring and controlling".
It is more a question of semantics. This process is all about monitoring & controlling. As soon as you need to "do" something you will hand the actual execution over.
Let's assume that you have a risk response plan "Buy insurance if weather gets bad". Here in monitoring & controlling we will see the trigger condition (weather forecast), then we issue an order to have the plan executed (that will happen in the executing processes) and later we will review the effectiveness of this implementation back here in this process.