In situations like this, I stick with common sense. I am not a code inspector, and typically don’t have time to research code requirements for such things. If I had run into this, I would have SAID something on the lines of “I’m pretty sure that code requires this…”. On paper I would have said something on the lines of it being a “safety” concern.
It wastes too much time getting into a pissing match with a builder or home owner over weather or not something it built to “code”.
If the builder is demanding the “code”, I would respond that he’s the builder, he should know the codes for it, and he should quote where it says it’s ok.
Even then, code is the MINIMUM requirement to be legal. Not necessarily safe or a good idea.