As I understand this proposal is only concerning emergency upgrades, which is then described as being a case where a chain halt occurs. I think in this case a clear distinction between “critical” and “emergency” (referred to in this other draft proposal - A formalized process for issuing **critical** Cosmos SDK software updates) is required since they can be interchangeable.
I agree that this edge-case should be pre-emptied.
It could be the case that AiB is not the first organisation to find a solution if such a case occurs, so I think that the proposal should explicitly place AiB as the gate keeper for vetting and issuing the any upgrades that are required in such a case.
I am not sure of where AiB stands with regards to holding this responsibility.
Another option here is to set up a cross-community “emergency team” that is delegated with the vetting and issuance of such upgrades. Then the discussion would revolve around the election, remit and precise power of such a team. Perhaps one could argue that the set of validators already is this team, however a proposal with a clear definition could be devised and delegators could vote in favour or against accordingly.