I disagree. Halford, or an LBS for that matter, will claim that but for the customers insistence, the bike would have had a full pre-delivery inspection, all the gears, brakes, etc., thoroughly checked over, limit screws, straightness of gear hangar checked, before being passed over to the customer, had they been allowed to build it up. Given that it is essentially thrown together in a factory in Taiwan. assembled and setup and operating correctly are two completely different things.
And any sensible employer is going to walk away from the issue, as a useless distraction, whilst insisting on the employee continuing with the payments.
I am saying the LBS is liable f they assembled the RD and not the customer. In my post I am asking if OP assembled the drivetrain i.e. RD.