"ICC is very good at making bad changes and backpedaling in the next edition (or errata)."
Two completely different Committees having different viewpoints about the type of buildings covered by the scopes of those codes (IBC versus IRC). The Code Officials are making the final vote to be inconsistent. Who really knows that they are thinking? Maybe there are some considerations about the cost/feasibility/loss-of life-potentials "analysis" going in their heads. OR, they might be just following the recommendations of the committee for that code. The voting Code Officials might not be the same people for each code! Large jurisdictions might have separate departments handling Commercial buildings versus IRC buildings. The Code Officials sometimes figure out that what they decided on has "unintended consequences" and approve proposals to fix the problem (or even reverse the original position.) With a consensus process and non-unanimous voting criteria, I guess that happens sometimes.
Errata, as I understand it, is where ICC Staff makes a mistake in publishing the results of the code development process. The approved proposal changes the code in certain ways and the code book shows something technically different (or doesn't reflect the proposal change at all). I wish they could get a better handle on those issues.