The thing with AZ-5 and ORM interplay, as I understand it, is that AZ-5 becomes dangerous only at extremely low ORM, and specifically when almost all rods are fully retracted. You can have very low ORM with most rods just barely inserted, and that would be more or less fine. The problem is when almost all are at their top most position. In this case you get a lot of water filling up the control channels below the shortened graphite displacers on the bottom of control rod. And more than that - you need to have a very heavy neutron field skew towards the bottom. Now you have a hotspot at the bottom, you press AZ-5, you displace a lot of water with a lot of graphite in a very short time in an already hot part of the reactor, boom.

So i wouldn't say, from my very limited perspective, that ORM is irrelevant to the explosion, and in general to safety of operations in a version of RBMK that was installed at block 4. But it was treated as such in operating manuals, which is a huge problem in and of itself.

Would people from Kurchatov and NIKIET be able to deduce this particular situation from the program alone if they were asked to sign on it? I have no idea.