I think it does apply to transits. Which I believe is stated in the ANO. As ATC cannot decide what flight conditions are present at the outer limits of the zone and SVFR flight may be possible and still complying with the SVFR criteria. Correct me if i'm wrong, but I will check the ANO.
The only mention of this in the ANO is Rule 24(3) of the Rules of the Air:
(3) For the purposes of an aeroplane taking off from or approaching to land at an aerodrome within Class B, C or D airspace, the visibility, if any, communicated to the commander of an aeroplane by the appropriate air traffic control unit shall be taken to be the flight visibility for the time being.
Note the limitation to take-off and landing.