It's jurisdiction specific. Although in theory a AHJ can supersede the code, local regs must state their authority. So an AHJ says you can do such and such, and you can prove he is in violation, you could fight it (at your expense and time) and likely will win. The down side of it all is that you will likely still be working in their juristdiction when all said and done
I have never actually seen anyone cite 90.4 but I have seen guys say "That is the way I read that section" and come up with a plausible explanation. That gap between different readings can get pretty wide, that is why I think people getting together on these BBs and talking things out is very valuable. The local trade groups are good about this too. I still see different rules in the various jurisdictions in spite of a state code. It would be great if everyone was using the same code
In my area, the accepted interpretation is that the authority having jurisdiction mentioned in 90.4 is not the local inspector, but is the actual state or city government that adopted the code. Also, that none of Article 90 is considered to be enforceable, since it is merely an introduction to the NEC.
Here in NJ the state adopts sec. 90 of the NEC with some editing. We change the words AHJ to electrical sub code official. That gives us the power of the AHJ. As for 90.4 myself I try to interpret the NEC as written, but as always you and I can see things in a different light. I then welcome the EC to engage in conversation with me. Tell me what he thinks and I will tell him how I see it. If I think he makes a good point, I can agree with him. As Greg says, I have brought many questions to this BB because I get a lot of questions from EC's out there. I also want to see if I am missing a point or two from the EC.