I ran shops for over 25 years and was a tech for 10 years before that. Techs are paid to work and service managers/writers are paid to advise and act as a go between for the tech and the customer. I would never want my techs to talk to a customer because they sometimes are not "people persons" and they could throw a wild guess while talking that the customer latches on to and then when diagnosed the fix is more expensive because of some other problem. The service writer in this instance could have handled it better but he gets a paycheck and if he is told to not allow techs to talk to customers, then that is what he will do to keep his job. I have never once in my whole life heard of a customer willing to support a worker after they get fired for going against what they are told they can and cannot do at the job.
The service manager, like I was, should be at least rudimentally trained in vehicle systems. I am still an ASE Master Tech and I asked a lot of questions to really pin down what was happening and when it was happening. I always wanted to duplicate the problem so I could find the problem. An untrained writer can cause frustration for a customer because then the customer feels completely left out of the process. It can be that way sometimes. If you are not going back there then get some recommendation(s) from friends about other shops. I never felt that all dealer techs were the best out there. I never worked at a dealer and I know back then I was one of the best in the area but I think my OCD helped with that. Find a shop you trust and look for ASE certs and stick with them and learn as much as you can about your rig so you feel more involved in the processes.
By the way, if you drive up to a shop ad the bays are empty and the techs are playing frisbee and they can "get you right in" may be a sign of a bad shop to deal with. Typically, the best shops are busy busy.