What I said is not the opposite of published guidance to controllers. There is no published guidance advising controllers to genuinely be as a friend to the pilot.
The two pieces of writing you highlight offer little actual guidance to controllers. It's mostly fluffy pillow speak about how wonderful the FAA is.
However you overlooked one important sentence offering true guidance to the controller:
"This detached and professional approach is the best way we can support Flight Standards in conducting an investigation that leads to a positive, safety-enhancing conclusion."
In other words, the controller can best assist in the initial stages of investigating the pilot by being polite. Notice the controller is directed to assist the FAA, not the pilot.
I'm not saying the controller is never helpful to the pilot, I'm just pointing out the inescapable fact that controllers have no monetary incentive to be your friend and everyone runs on incentives.