They're wrong. A good sign of this, is the distain this deeply politicised snarky rule is being treated with, by the British public and the NHS staff who can see it for what it is: performatively useless.
If they'd said they wanted more plain English it might have had some support.
The amount of ink and paper consumed defending it, will exceed the savings. Next, they'll be arguing the colon and apostrophe shouldn't be used.
https://www.theguardian.com/politics/2022/sep/16/therese-cof...
https://www.theguardian.com/politics/2022/sep/15/coffey-urge...