The theory behind talking on the phone while driving being dangerous is the expectation during a conversation when the line is open on both sides. When we have a passenger in the car both people are watching traffic, and if the person driving pauses to better focus on traffic, the passenger naturally pauses also, because they also witness the traffic and see the driver checking mirrors, slowing down, changing lanes, etc. When a driver is talking to somone on the phone there is a psychological pressure to maintain the conversation as though one is sitting in their living room. The other person does not naturally pause depending on the events going on on the road.
With a CB, people wait to hear the reply. The obligation for the two way conversation is slightly different. However, it probably could be argued that there is some increased danger, compared to not talking to someone else while driving.