He's wrong and using emotional appeal in some of the points. If someone is trying to take on a role that they aren't trained for, it isn't improper to say so...collaboration sounds nice but it isn't collaboration if one party has to have the other party's signature. That's not collaboration, it's supervision. The argument about PAs being able to do everything nurses are allowed to is also irrelevant and doctors don't think nurses know how to do what they are allowed to do. The impetus to show they are equally capable and safe is on the midlevels. But either way legal permission in this country is determined by lobbying ability, not skill. The concept of PAs attending a medical residency is ill conceived.
There is nothing wrong with being a well trained and competant assistant.