wow, that's an odd spot to be in. i agree with your stand on the matter. i myself know of no restrictions in the IBC for how to form dba bar. his reference to the rule of thumb for rebar to be cold formed may be correct, but where would his code reference be for that? on a side note you could send a extra work order to them explaining that additional items need to be replaced due to a rejection that is not based on a code requirement, per your contract.(if that is indeed the case). that would get some attention, and get some scrambling to find the restriction that they say exists somewhere. worst case is they find something that you where unaware of and the pieces would need to be replaced and all would be well.
i am very curious as to how your situation pans out please keep us informed.
JJ
edit, section 1907 of IBC covers cold bending of reinforcement bars, not anchor bars(dba).
i'm still diggin. i can't even find a reference to deformed bar anchors in the IBC at all.