At the front of your manual bose-x, you note that the Jepp chart NOTAMs have shown that chart to be withdrawn for ages.
Jepp typically use that mechanism where there is some doubt over whether or not the approach will be re-instated at some future date. It is a classic Jepp Gotcha, but it is nice to see that there is optimism for Sheffield's future as far away as Frankfurt
Whilst flying the procedure may be inappropriate, I think you are clutching at straws by suggesting that it places pilots in breach of Rule 5 MATS Part 3. The phrase, "I'm sure a good Lawyer could argue[something totally illogical]" is always a bit of a cop-out.