Perhaps in an ideal world, hower not many electricians would get into splitting down a ring at 10pm in an occupied domestic with furniture in front of sockets, etc after a hard day at work, when the resident also wants him to finish up quickly and set them settle down for the night. I don't see lack of RCD protection to one circuit for one night being a risk that cannot me managed. The direct instruction not to use those sockets for outside with an RCD adapter should suffice. The fault can then be attended to in working ours with a clear head and a more reasonable rate for the customer.
What about the possibility of leaving a wall live due to the fault that has occurred? Just because the RCD has gone does not mean that the fault has does it?