This scenario wasn’t explicitly considered in the writing of the charter. I would be in favor of modifying the proposal to allow an Indexer to submit the last valid PoI when closing an allocation if their allocation was created before the subgraph error occurred. Let me know if this addresses your particular concern.
More generally, I totally agree with you here that this is an area where we’ll need to iterate as more community members become familiar with the mechanisms.
Without betraying any information shared in confidence, I can say that the timing of the disputes was because the Fisherman in this instance wasn’t sure if they were allowed to dispute Indexers for faults that occurred before the Arbitration Charter was ratified. This was clarified in the Protocol Townhall, hence the timing of the disputes. The reason for the new address, as I understand it, was to not create ill will among Indexers.
That being said, none of the mechanisms in the protocol are intended to be punitive to honest participants–this is one of the reasons that the Arbitration Charter allows the Arbitrator to exercise discretion. Over time, as Graph Node and Indexer tooling matures and Indexers build confidence interacting with the protocol, there will hopefully be fewer and fewer instances in which the Arbitrator must exercise this discretion.
For now, I know the Arbitrators are aware of the immature state of tooling in the protocol, and while I cannot speak for them, I do not expect that they will punish Indexers for inadvertent PoI inconsistencies, especially since as @cryptovestor notes, this is the first time many of these issues are being encountered in the decentralized network.