'he' in that sentence ('that isn't the procedure he chose') still referred to Joe. Zubon's description doesn't justify the claim, it's a description of the consequence of the claim.

My original objection was that 'they' ("I think they would have given up on this branch already.") have a different procedure than Joe has ("all you have to do is do a brute force search of the space of all possible actions, and then pick the one with the consequences that you like the most."). Whomever 'they' refers to, you're expecting them to care about human suffering and be more careful than Joe is. Joe is a living counterexample to the notion that anyone with that kind of power would have given up on our branch already, since he explicitly throws caution to the wind and runs a brute force search of all Joe::future universes using infinite processing power, which would produce an endless array of rejection-worthy universes run at arbitrary levels of detail.