There is no immediate or potential danger of electric shock, injury, overload related fire etc.. that could make the installation unsatisfactory for continued use..
And there is no code required for an unswitched socket as the connected appliance can be isolated by simply unplugging it.
So it can be considered as not requiring any code, as there are no electrical safety issues?
Have you got a copy of best practice guide 4..?
https://www.electricalsafetyfirst.org.uk/media/mi1oqkur/best-practice-guide-4-issue-7-1.pdf
and have you read some of the myths listed at the rear of the guide..?
The last one bottom of page 23 states: Any observation not directly related to electrical safety and hence to the suitability of the installation for continued service.
Also if you read the example C3 codes.. I am not convinced that a un-operational switch, is in the same calibre as a typical C3?