Maybe this is my own thinking, but I would assume that his licensing board is under no obligation to respond to your proposal because to do so would indicate the therapist is guilty without allowing him a chance to tell his side of the story--they'll presume ethical and practice competence unless otherwise proving in a public hearing.

If they were to grant the proposal, it would be "unjustly" (in a court of law) undermining the therapist and it opens the licensing body up to litigation because therapist do have rights with complaints and there is a set formal process that needs to be followed when a complaint or report is made or is being made. So, I would bargain that a formal complaint needs to be submitted anyway because the board will not have the ability to force a therapist's hands without a fair hearing where both parties (you and your T) are present.

I know that you mentioned his professional body is the HCPC and they have a list of standards in regard to the information needed before they start the complaint process. I'm just not sure if they would be willing to respond to an informal proposal because of the legal implications.