Yes, it is a custom panel shop.
IMO, the internal wiring completely inside the cabinet is just not subject to the NEC, nor are there any NEC sections that would actually apply to that wiring. The wire that comes into the cabinet from the outside is subject to the NEC.
How is this any different than an MCC?
As long as the minimal requirements the NEC has for an ICP are met, there would not appear to be anything a mere inspector could do anyway, especially if the ICP was listed. And why would they want to?
Think about a few things.
UL508a allows the use of conductor insulation types inside an ICP that are not allowed by the NEC. AWM comes to mind. Under what authority would an inspector be able to reject the use of AWM inside an ICP?
The plastic duct typically used inside of an ICP is not a NEC raceway. Can the inspector reject an ICP because plastic wire duct was used inside it?
It is common to use cord and cables not allowed by the NEC inside an ICP. Should this result in a red tag?