This doesn’t make sense:

“…a bodhisattva ‘vows to become enlightened in order to relieve the suffering of all sentient (conscious) beings,’ but delays full enlightenment to retain the sliver of egoism that’s needed to motivate that compassion.”

How can one have a sliver of egoism? The egoic sense of self either exists or it does not.

If a person is compassionate, does this mean he is motivated to be so? It doesn’t seem that this is necessarily a conscious thought or wish. And does compassion come from the ego self or is it from seeing that there is no difference between anyone and anything, including the self?

While a Buddhist may believe “the pursuit of nirvana is supposed to generate or support compassion, loving-kindness, and joy, along with equanimity or neutrality,” this doesn’t necessarily make them correct in their belief. When there is a pursuit of something it means thought is engaged in effort; when there is thought there is the egoic self. It’s not the pursuit of nirvana that creates compassion, and I question whether acting compassionate, nonjudgmental, or joyful would result in nirvana, if there really is a state called nirvana that can ever be known.

This seems to be a contradiction: “From that divine perspective, everything becomes like a piece in a giant jigsaw puzzle, and you behold the whole, finished work in which everything has its proper, causally determined place.” The fragmentation of the whole into pieces is not a divine perspective, but the perspective of the self; and it cannot be the self that beholds the whole, because the self is itself a fragment.

You wrote, “…even if anyone could understand nature at that level, there would be no overall inherent value or function of the cosmos…” It is the self that creates the idea or image that there is an inherent value in things. But as I see it, function is a different idea than value, if function is defined as "work or operating in a proper or particular way."

This also seems like a contradiction of terms: “…the blessedness of enlightenment is subjective in that the mere philosopher judges the whole through mental detachment,…” If enlightenment means a state in which the egoic self is replaced by a holistic paradigm devoid of a self, then there is no one to judge or to be mentally detached. Anyone who judges is doing so by means of attachments — the attachments that create the self. But I do agree that enlightenment is subjective.

It seems like so many of these ideas about the enlightened perspective are misbelieved to be related to detachment and indifference, whereas, instead, I see it as full engagement and acceptance. Indifference implies not caring, but compassion implies caring.

Re: “The stereotype of Buddhists is that they’re like Jains in assessing all living things as having equal value.” This is a curious statement because it suggests that there is valuation. Again, it is the self that assesses something’s worth. Rather than saying everything has equal value, I would say that everything is of one essence, but the essence expresses itself in manifold ways — as different people, animals, rocks, pianos, glass, trees, and so on. It is the self that prioritizes or values one that is greater or more important than another. To exist as a body in this world there must be thought, judgment, preferences, and so on. Without this kind of thinking we would not survive.

Instead of going over more points I would suggest reading the books of Nisargadatta and the story of Arjuna and Krishna. Nisargadatta was not a Buddhist, but his teachings would shed some light on this discussion. And the Krishna-Arjuna story provides some insight into what it means to say "Yes!" to life while in full awareness of all the ramifications of one's actions and decisions.

I have read a great deal about the idea of enlightenment and the Buddhist perspective, almost all coming from Buddhists and Buddhist scholars who say they are not enlightened and yet teach others how to become enlightened and what it means to be in the enlightened state. I find this quite disingenuous in the same way as if a garage mechanic were to teach others about quantum physics because he greatly admires that branch of science.

I am not a Buddhist so I cannot answer to your comment about how Buddhists are trained, but I do know that there are many different sects of Buddhism with different teachings and aims. Are all Buddhists trained like Pavlov’s dog? I would say from my own experience (I cannot speak for others), however, that to reach complete mental clarity in a state that does not include the egoic sense of self, there can be no training involved in the process. There’s not even a process except if you consider the process of elimination — observing the sense of self so deeply as to eliminate everything that it is not until it dissipates long enough to provide a clarity that is akin to emptiness.