Unfortunately, neither the CAA, Port Authority nor even the local council Environmental Helath Dept would have any interest in the original query.
As other posters have already detailed, it is perfectly legal to operate the aircraft in question with an inoperative WC sink. Indeed it is the CAA who approve this particular operation. Provided the waterless hand gel was installed on the toilet sink (it looks identical to the standard soap dispenser), then there is also no hygiene issue that any of the other authorities would consider serious enough to intervene.
You may be inclined to disagree, but let me tell you this. Even when you have a perfectly serviceable and apparently clean WC and sink, remember the cleaners wipe down your tray table and all other surfaces with the very same cloths they use to wipe down the WC on this and all other aircraft they service.
Enjoy your next in flight sandwich.