I think you’ve identified something really important with the Aristotle point, and it connects directly back to the OP about the “great-souled man” needing correction.
The problem is precisely that Aristotle’s God is modeled on the best thing Aristotle knows — contemplative self-sufficiency — and then human perfection is modeled on that. But if the highest reality is essentially non-receptive, and has no relation downward, then the whole positive valuation of receptivity we’ve been developing has no ultimate grounding. Receptivity becomes, at best, a concession to finitude — something you need because you’re not God, not because receptivity reflects anything in the ultimate nature of things. And that means the trajectory of perfection points toward ever-greater self-enclosure, which is exactly the problem you identified in the OP with Aristotle’s great-souled man. The sage who can only give and never receive isn’t actually more godlike; he’s imitating a God who is, frankly, impoverished in a way Aristotle can’t quite acknowledge.
Your point about flat ontologies collapsing into voluntarism is, I think, exactly right and under-discussed. If you don’t have a transcendent actuality that is itself relational — that models receptivity and self-gift as features of ultimate reality rather than concessions to finitude — then you’re stuck with two options. Either perfection is self-enclosed actuality (Aristotle’s route), in which case potency/receptivity is always ultimately a deficiency. Or you react against that and elevate potency, indeterminacy, and freedom-as-open-possibility to the highest place, which is the voluntarist move. And the voluntarist move feels liberating at first but actually undermines the value of the individual it claims to protect, because if freedom is just indeterminacy then there’s no determinate good toward which freedom is ordered, and the individual becomes a sheer point of arbitrary will with no telos — which is, arguably, where a lot of modern liberal thought has ended up.
The Trinitarian resolution — where ultimate reality is both fully actual and constitutively relational, where self-gift and receptivity are features of the divine life itself and not just creaturely accommodations — really does seem to be the only framework that holds both sides together. Not because its theologically convenient but because the philosophical alternatives keep generating exactly these oscillations between self-enclosed actuality and ungrounded potency. If God is pure self-sufficient act with no relational dimension, receptivity has no ultimate ground. If you flatten the ontology and remove the transcendent term entirely, the dialectic just spins in place.
Though I’d be curious whether the Neo-Confucian thinkers who emphasize the Taiji (Supreme Ultimate) might have resources here that go beyond what a strictly flat ontology provides. If the Taiji is genuinely ultimate and not just the highest emergent pattern, then maybe there’s space for something analogous — a ground in which the Li/Qi relationship is itself grounded and resolved. But that might be pulling the tradition in a direction it doesn’t naturally want to go.