Let me guess, god distances himself from creation and weeps because he can do nothing for interference would remove free will, true love etc.
Post his argument or central thesis if you will
I'll try, but if you are at all interested, I suggest you read it yourself.
G-d created nature and the laws that govern nature. Nature is imperfect, by definition and since human beings are part of nature, we are also imperfect.
Let's assume that G-d intervened continuously in nature so that nothing bad ever happened to anyone. Or maybe just to evil people. So if someone fell off a building who was good, G-d rescued him or her. But if someone like Hitler did it, He would let him fall to his death.
If G-d did that, there would not be any regularity in nature, no natural laws for humans to discover so that they could find cures for diseases, invent agriculture, technology, etc. Because you could not predict anything, since G-d would micro-manage every single event to make sure that good always won out.
In that kind of universe, people would wind up being like the Eloi in H. G. Wells' "The Time Machine.". They would become utterly passive, dependent like children on what G-d did or did not do for them.
G-d did not want to create that kind of universe, as He makes clear in Genesis by giving mankind the knowledge of good and evil, which requires self-awareness, and dominion over the world. So it's more than making free will possible; it's about making the world intelligible and hospitable to humanity.
Kushner also discusses how G-d helps us when we suffer and how He does suffer with us. Why? It is a fundamental part of His nature. Here I would have to refer you to Kushner directly, since I don't remember enough of that thread to give you a good account of it.
And I have to also say again that I don't think any of the above really does justice to the book overall; Kushner approaches these issues from many viewpoints and does a far better job of developing his ideas than what I have tried to capture in this summary.
It is not really Deism; it is more about the logic of what it means to have created the kind of universe we live in so that we, as part of creation, can understand and live in it using the gifts that G-d has given us.