By way of background: PSL considers a case where a villager can save either his father's life or that of a (relevantly similar) stranger. He then considers a form of consequentialism which tries to accommodate the intuition that the villager ought to save his father by assigning value not just to welfare but also to states of affairs in which sons help their fathers. PSL then raises the motive objection (p.380):
Why would he help his father in preference to a stranger? Given the symmetry thesis this will be because of the reason why he ought to help his father. So if the consequentialist account of why he ought to help his father is correct, then the reason why he would help him in preference to a stranger would be because he will be producing a better state of affairs in the world than if he did any other act. [...]
The deciding factor in whether this state of affairs is best is the fact that his act will have as a consequence a state in which a son helps his father. But this should not lead us to think that the relation that figures in this state will figure in the villager’s motivation after all. The fact that his act will have this consequence is the reason why the act will have the best outcome, since it breaks the tie between the value of the benefit conferred on either his father, or a stranger. But it is the fact that his act has produced the best outcome, not the fact that it has produced a state in which a son helps a father, that makes it the right act to do. Otherwise this really would look like a mere semantic victory for the consequentialist. What makes it stand out from the intuitionist account is that it is the production of impartial value that grounds this duty. This is not merely a rewording of the intuitionists view.
While I wouldn't defend this particular form of consequentialism, I think PSL is mistaken about what fitting motives follow from the view, and also mistaken to think that the view would otherwise collapse into Rossian intuitionism.
For any moral theory, we need to distinguish between (i) the particular right-making features it posits, or what makes some particular action right, and (ii) the general property shared by all right actions, or what makes actions in general right (when they are right). Applied to Consequentialism: what makes actions in general right is that they produce the best outcome -- this is what all right actions have in common. But each particular action will be right in a different way. The good-making features of the outcome (the values it realizes) will differ from case to case, and hence so do the right-making features of the actions that bring about these good outcomes. PSL confuses these when he gives the general answer to the particular question of what makes the villager's act of helping his father right. The correct answer, according to the form of consequentialism he's considering, will appeal to the particular values at stake in the decision, including the value of sons helping their fathers.
Note that this same distinction applies to PSL's Rossianism. Imagine if I argued against his view as follows:
The deciding factor in whether the balance of prima facie duties favours the son's helping his father over the stranger is the fact that he has a prima facie duty of fidelity (or whatever) to his father. But this should not lead us to think that the relation that figures in this state will figure in the villager’s motivation after all. The fact that his act will satisfy this prima facie duty is the reason why the act will satisfy the balance of prima facie duties, since it breaks the tie between the prima facie duties of beneficence that apply equally to his father and the stranger. But it is the fact that his act satisfies the balance of prima facie duties, not the fact that it satisfies his prima facie duty of fidelty to his father, that makes it the right act to do.
This would be a bad objection to Rossianism. Sure, what all right actions have in common, on this view, is that they best satisfy the balance of prima facie duties. So one might, speaking loosely, say that it is possession of this general property that explains why an act is right. But it would also be misleading to say this, for it may lead one to overlook the fact that in any given case there will be a more particular explanation, invoking particular right-making features, and it is these particular right-making features that feature in the motivations of the virtuous agent.
And so it is in the case of consequentialism! I'm not sure why more people haven't previously realized this, but if my work only ever leads to the wider appreciation of one insight, I hope it is this: that the virtuous (or fitting) consequentialist agent desires each particular good, and not just the promotion of abstract value as such.
Of course, the form of non-welfarist consequentialism that PSL discusses here can still be exposed as perverse (and distinct from Rossian Pluralism). For it implies that it's fitting to desire that sons help their fathers (generally), and hence he should let his father die if it would thereby enable two other sons to aid their (respective) fathers. Nobody should hold that view. Either one should endorse full-blown agent-relative value, such that the son should value his father's welfare over that of the stranger, or else simply stick with good old-fashioned utilitarianism, according to which the son should care deeply about the welfare of his father and the stranger, equally.
Similar remarks apply to PSL's resentment objection (p.382):
[T]he fact that the villager has failed to bring about the best state of affairs leaves the fact that his father has been wronged completely unexplained. If anyone is wronged here, it would be the world which has not been made as good as it could have been. But that, of course, makes no sense.
It's not clear whether PSL sees this form of objection as applying just to the specific view he discusses, or to consequentialism more generally. So let me just flag that it's not generally true that consequentialism can't account for personal wrongs (and hence warranted resentment). Even on utilitarianism, if someone chooses to prevent a lesser harm to another instead of a greater harm to Bob, then Bob -- and not just the world -- has been wronged by them. They have failed to take Bob's interests sufficiently into account, which is a kind of disrespect to Bob -- a failure to appreciate his distinctive value as a person, or to respond to it in the manner that is due.
To think otherwise is, again, to let the general facts about value blind one to the more particular value facts -- such as the distinctive value of each individual person, which we must (morally) take into account, for the individual's own sake.