But, after all the shouting's over, why would you want to do it? Whether the law does or doesn't ban (or allow) specific classes of approach ... what makes sense?
ADF is notoriously inaccurate: I flew an NDB procedure on my FAA IR checkride, with the needles in the right places all the way to the MAP. After I'd done the missed procedire and got to the holding fix, the examiner asked me how far left or right of the centreline I thought I was at the MAP. I said I thought I was ON the centreline. He agreed that's what the instruments showed, and said that in fact I probably wouldn't even have seen the airfield, which was a good half mile to one side. We then had an "examiner debate" about ADF errors, when I surprised him by telling him about Coastal Effect - I suppose they don't get a lot of that on NDB procedures in the USA.
I've flown an NDB procedure "in anger" just once - the 02 at Shoreham. I was very glad indeed that I had the GNS430 running alongside, with the 02 NDB procedure displayed. (I've flown countless NDB procedures in training and "renewals", under the hood, but that's a lot easier).
Stuck above an overcast, with 400 foot cloudbase all around? I'll go (above MSA) somewhere with an ILS and vis above minima, thank you very much. Cowardice Prolongs Active Life and all that.