I think it can be done in a much simpler way: "What do you need?" If he says, "nothing" then you reply "Ok. Let me know if that changes. I'll help in whatever way you want." and then move on. He's not going to budge right now, but he might in the future. You've planted a seed with him that you're available. He might never reach out. There's nothing else you can do that is productive but accept that.