I don't have any deeper insight than these colleagues.
I have been resistant to the whole collar business. It has always felt inauthentic to me, as though we were picking and choosing how to relate to Christianity, adopting it opportunistically. More than once, I pronounced, as is my way sometimes, that a UU minister who wouldn't wear a clerical collar to church on Sunday shouldn't wear one on Saturday down at the Federal building.
But I recognize now that I long had a little Christ-shaped chip on my shoulder. I saw everything through the lens of the Unitarian Universalist failure to acknowledge its relationship to Christianity. Given that perspective, I saw the collar as a misappropriation, not much different that chocolate communions.
Recently, I have been more persuaded by the logic of the collar that says it has social power which we should wield wisely. It can add social power to protest. It can, by upending expectations, subvert reactionary forms of Christianity. It can make certain relationships and interactions possible which were not otherwise. Many of the stories told by the Red Pill Brethren have this theme.
But all of that social power and symbolism is derived from the fading authority of the church.
My development away from carrying the Christ Chip on my shoulder was that I observed that the church was entering (in the global North, at least) into the tomb. Christianity is being stripped of all social power and all authority. As the letter to the Philippians says, "he laid no claim to equality with God, but made himself nothing". Unitarian Universalism itself is an expression of this move toward the tomb -- a church stripping itself of the claim of providing a more direct access to God.
(Christians ought not to be afraid of the tomb; it's just a rest stop on the way to new life.)
So while it is useful, perhaps, in the short term to lay claim to the social authority of Christianity by wearing the clerical collar, it is will have diminishing returns. Our ability to inspire others will have to come from some other source: our authenticity, our consistency, our humility, our transparency.
How would we convey what we are trying to communicate with the clerical collar if we did not wear it?