Well at this point I am not asking him to do so, I am asking that he make some decisions so we can get onto the next phase of getting the game ready.
We can have the domains finalized, the characters done, and everything ready to go, and if any of it seriously screws with something Matt had in mind then that particular detail can be fixed but the rest of it will stand.
By then, or ideally before then, Matt will hopefully be in a position to step back into the main DM role then, but if not we can decide how to proceed, but that seems to me to be a more useful course of action than sitting around waiting for Matt when he clearly has no time at the moment to devote to RoE. That is, after all, the whole point of having more than one DM, right?