I've always thought the zone height was a daft one - in most houses downlights are usually just outside the zone, and therefore not required to be a particular IP rating.
Would have made more sense to make it to the ceiling, or set a height more than the average house ceiling (2.5m maybe) . It's not like steam stops at 2.25cm!
@brianmoooore is correct in that if they have given it a C2, it should be under "suitability of current-using equipment for particular position with the location (701.55)", rather than "suitability of accessories and controlgear etc. for a particular zone (701.512.3)"
Or it could go under "Suitability of accessories for external influences (512.2)" I guess.
I'd feel C3 would be more appropriate though tbh, unless they are rusty. They are presumably RCD protected anyway, and if you are tall enough to change bulbs while in the shower and do so then not sure an EICR is going to save you!
Was it a NAPIT inspector? Could be the NAPIT guide striking again and someone not using actual judgement. (Don't have a copy to check what they say)
It's a common code I saw with the quicky EICR mongers that popped up to fill the PRS need - They no doubt wanted to sell some shiny new downlights.
Maybe the same ones who will swear blind you can't have a light switch in a bathroom, or that there is a zone around a sink.