I agree OP. It is a spiritual practice and therefore should not be promoted by the NHS unless they're promoting other spiritual things
I have bipolar, I was pretty ill last year. An important part of my treatment was the weekly qi gong and then tai chi sessions I had provided by occupational therapy. I'm sure if you look in journals then it wouldn't be mentioned but it was one of the few times I relaxed and my brain slowed down for a while. It was delivered by occupational therapists and assistants.
The NHS also funds chaplains.
I am surprised the reiki is funded directly by the NHS and not a cancer charity like Maggies though.